GEMS  AND  GEM  MINERALS 


GEMS  AND    GEM 
MINERALS 


OLIVER  CUMMINGS  FARRINGTON,  PH.D. 

CURATOR  OF  GEOLOGY,  FIELD  COLUMBIAN  MUSEUM 


"  FOR  LITERAL  TRUTH  OF  YOUR  JEWELS  THEMSELVES, 
ABSOLUTELY  SEARCH  OUT  AND  CAST  AWAY  ALL  MANNER  OF 
FALSE  OR  DYED  OR  ALTERED  STONES.  *  *  *  AND.  AS  A 
PIECE  OF  TRUE  *  *  *  KNOWLEDGE,  LEARN  TO  KNOW 
THESE  STONES  WHEN  YOU  SEE  THEM  UNCUT." 

— BUSKIN 


CHICAGO 

A.  W.  MUMFORD,  PUBLISHER 

1903 


CC 


COPYRIGHT,  1903 

BY  OLIVER  CDMMINGS  FARRINGTON 
CHICAGO 


£f)c  Eakest'tie  $rrse 

DONNELLEY  &  SONS  COMPANY 
CHICAGO 


CONTENTS 


NATURE  OF  GEMS     -  1 

OCCURRENCE  OF  GEMS  -                                                                                      4 

MINING  OF  GEMS      -  8 

COLOR  OF  GEMS  -  13 

LUSTER  16 

HARDNESS  17 

SPECIFIC  GRAVITY     -  19 

OPTICAL  QUALITIES  26 

ELECTRICAL  PROPERTIES,  PHOSPHORESCENCE,  AND  FLUORESCENCE  34 

CRYSTAL  FORM    -  37 

CUTTING  AND  MOUNTING  41 

VALUATION  AND  PRICE  -                                                                                    50 

IMITATION  GEMS  AND  How  TO  DETECT  THEM  54 

SUPERSTITIONS  EEGARDING  GEMS  57 

BIRTH-STONES  -                                        61 

DIAMOND  66 

CORUNDUM    -  88 

SPINEL    -  -                                                                                    95 

BERYL  98- 

EUCLASE  -      104 

PHENACITE    -  105 

CHRYSOBERYL      -  -      106 

ZIRCON  109 

TOURMALINE  -                         -      111 

LEPIDOLITE   -  -            117 

SPODUMENE  -            -            -      118 

TOPAZ  119 

CYANITE  -            -            -      123 

ANDALUSITE  -                         124 

STAUROLITE  -      126 

GARNET  -                                     127 

CHRYSOLITE  --                                     ---132 

EPIDOTE                     -  -            -            -             134 

VESUVIANITE       -  -            -            -            -            -            -            -135 

IOLITE                       -  -            -            -            -            -            -136 

EUTILE    ....  -.-.      137 


33 


PAGE 

TlTANITE          -  138 

AXINITE  -                  -                  -         139 

SAMARSKITE,  GADOLINITE,  ALLANITE,  FERGUSONITE,  POLYCRASE,  AND 

EUXENITE       -  140 

QUARTZ  -  -      141 

OPAL  159 

JADE      -  165 

DIOPSIDE      -  168 

HYPERSTHENE  AND  BRONZITE       -  -      169 

TURQUOIS      -  170 

VARISCITE  -      174 

CALLAINITE   -  174 

FELDSPAR  -      175 

OBSIDIAN      -  180 

MOLDAVITE  -      183 

APATITE  -                         185 

FLUORITE  -      186 

HEMATITE     -  188 

PYRITE    -  -      189 

CHLORASTROLITE  -            -            -                        191 

THOMSONITE  -                         -            -            -            -192 

PREHNITE      -  -                                                  193 

EHODONITE  -            -                         -      194 

ZOISITE  ...            -                         195 

PRECIOUS  SERPENTINE     -  -                                            195 

MALACHITE  -  -                                     -                         197 

CHRYSOCOLLA      -  -            -      199 

DIOPTASE      -  ....                         200 

LAPIS  LAZULI      -  -                        -      201 

SMITHSONITE  •                         203 

ALABASTER  -                                      -                                     -      204 

AMBER  -            -                         205 

JET  210 
PEARL 

PRECIOUS  CORAL  -            -            -                         -            -            -221 


vi 


HALF-TONES  AND   LINE   ENGRAVINGS 

PAGE 

ANDALUSITE,   SECTION  OF  CRYSTAL  OF  -     124 

AXINITE      -  -           139 

BERYL,  CRYSTAL  FORMS  OF    -  99 

BRILLIANT  CUT,  VIEWS  OF  44 

CABOCHON  CUT,  VIEWS  OF      -  46 

CEYLONESE  GEM  CUTTER,  A  42 

CONCENTRATION  OF  GEM  MINERALS  UPON  A  BEACH  -        6 

CORUNDUM  MINE,  NORTH  CAROLINA  93 

CRYSTAL  AXES  -      38 

CUBE,   OCTAHEDRON,  DODECAHEDRON,  AND  TRAPEZOHEDRON      -  39 

CUTTING  AGATES  AT  OBERSTEIN  -      48 

DIAMOND  BRILLIANTS,  EXACT  SIZES  OF   -  -            51 

DIAMOND  CRYSTALS,  COMMON  FORMS  OF  -      67 

DIAMOND  DIGGING  NEAR  DIAMANTINA,  BRAZIL   -  4 

DIAMOND  MINES  OF  KIMBERLY,  1872     -  81 

DIAMOND  MINING,  Rio  JEQUETINHONHA,  BRAZIL  -                         77 

DISTORTION  OF  CUBICAL  CRYSTAL       -  37 

DREDGING  PRECIOUS  CORAL                                   -  -                       221 

FAIRY  STONES  -  -    126 

FLUORITE,  CRYSTAL  FORMS  OF  -            -           186 

GARNET,   CRYSTAL  FORMS  OF  -    127 

GLACIAL  MAP  OF  THE  GREAT  LAKES  REGION     -  -            -             89 

HEXAGONAL  PRISM  AND  PYRAMID       -  40 

INSTRUMENT  FOR  EXAMINING  GEMS  IN  POLARIZED  LIGHT  -  32 

MAP  OF  INDIA,  SHOWING  DIAMOND  FIELDS   -  71 

MAP  OF  DIAMOND  FIELDS  OF  BRAZIL  76 

MINING  OPAL,  NEW  SOUTH  WALES    -  -            -    163 

MOLDAVITE  PEBBLES                                   -  183 

MOSS-AGATE,  INDIA     -                                    -  -    151 

NICOL  PRISM,  CONSTRUCTION  OF   -            -            -  -            -             30 


OBSIDIAN  CLIFF,  YELLOWSTONE  PARK                         -  181 

OPAL  MINES,  NEW  SOUTH  WALES  -            -           163 

PATH  OF  RAY  IN  DIAMOND  CUT  AS  A  BRILLIANT     -  -            -29 

PATH  OF  RAYS  PASSING  FROM  DENSE  TO  RARE  MEDIUM  -             28 

PEARLS,  EXACT  SIZES  OF,  FROM  2  TO  30  GRAINS     -  -     219 

PREMIER  DIAMOND  MINE,   SOUTH  AFRICA  -               8 
PRELIMINARY  CONCENTRATION  OF  DIAMOND-BEARING  GRAVEL           -       78 

PYRITE,  CRYSTAL  FORMS  OF  189 

QUARTZ,  CRYSTAL  FORMS  OF  -                                      -  -     142 

QUARTZ,  CRYSTAL  FORMS  OF,  PRODUCED  BY  DISTORTION  -             38 

REFLECTION  OF  LIGHT,  DIAGRAM  ILLUSTRATING  -            -      26 

REFRACTION  OF  LIGHT,  DIAGRAM  ILLUSTRATING  -                         28 

REMARKABLE  DIAMONDS  -                   72 

ROSE  CUT   -  46 

RUBY-BEARING  GRAVEL,  NORTH  CAROLINA    -  90 

RUTILE  -           137 

SEARCHING  GRAVEL  FOR  DIAMONDS,   BRAZIL  -       78 

SECTION  OF  DE  BEERS  DIAMOND  MINE,  SOUTH  AFRICA  84 

SHELL  SHOWING  IMAGES  OF  BUDDHA  -  -     213 

SPECIFIC  GRAVITY  BALANCE  -             21 

SPHENE  -    138 

TABLE  CUT  46 

TETRAGONAL  PRISM  AND  PYRAMID     -  40 

TOPAZ,  CRYSTAL  FORMS  OF  120 

TOURMALINE  MINE,  HADDAM,  CONNECTICUT  -  -    115 

TOURMALINE  MINE,  MT.  MICA,  MAINE     -  115 

TRAP  OR  STEP  CUT  45 

TURQUOIS  MINE,  NEW  MEXICO      -  172 

X-RAY  PHOTOGRAPH  OF  PASTE  AND  REAL  DIAMONDS  -      35 

WASHING  GRAVEL  FOR  RUBIES,  NORTH  CAROLINA  90 

ZIRCON,  CRYSTAL  FORMS  OF-            -            -  -            -110 


viii 


LIST    OF    FULL-PAGE    ILLUSTRATIONS    IN    COLOR 

FAG* 

BIRTHSTONES     -  Frontispiece 

Garnet,  rAmethyst,  Bloodstone,  Diamond,  Emerald,  Agate,  Ruby,  Sardonyx, 
Sapphire,  Opal,  Topaz,  Turquois. 

DIAMOND  AND  CORUNDUM  -  -      66 

Diamond  in  matrix,  Brazil;  Diamond  in  matrix,  South  Africa;  Carbonado, 
Bort,  Sapphire  Crystal,  Cut  Sapphire,  Ruby  Crystal,  Cut  Ruby;  Spinel 
Crystal,  Rubicelle;  Spinel  Crystal,  Balas-Ruby. 

BERYL  -  -       98 

Golden  Beryl,  Siberia;  Blue  Beryl,  Siberia;  Blue  Beryl,  Albany,  Maine; 
Aquamarine,  Connecticut;  Aquamarine,  Ural  Mountains;  Emerald  in  matrix, 
Ural  Mountains. 

TOURMALINE     -  -     111 

Green  Tourmaline,  Brazil;  Green  Tourmaline,  Haddam,  Connecticut;  Tourma- 
line section,  California;  Red  Tourmaline,  Island  of  Elba;  Red  Tourmaline, 
California;  Brown  Tourmaline,  Gouverneur,  New  York;  Black  Tourmaline, 
Finland. 

TOPAZ  -  -    119 

Topaz,  with  Mica  and  Feldspar,  Russia;  Topaz,  Brazil;  Topaz  in  Rhyolite, 
Utah;  Topaz,  Japan;  Waterworn  Topaz,  Brazil. 

GARNET,  CHRYSOLITE,  AND  EPIDOTE  -     127 

Almandite  Garnet,  Alaska;  Almandite  Garnet,  cut;  Essonite  Garnet  and 
Diopside,  Italy;  Essonite  Garnet,  cut;  Demantoid  Garnet,  Ural  Mountains; 
Demantoid  Garnet,  cut;  Cape  Ruby,  cut;  Pyrope  Garnet,  Bohemia;  Chryso- 
lite Crystal;  Chrysolite,  cut;  Epidote,  Knappenwand,  Austria. 

QUARTZ  (crystalline)     -  -     141 

Rutilated  Quartz,  Brazil;  Rose  Quartz,  Black  Hills;  Smoky  Quartz,  Switzer- 
land; Amethyst,  Virginia;  Amethyst,  Montana. 

AGATE  -  -     154 

Banded  Agate,  Lake  Superior;  Banded  Agate,  Brazil;  Moss-agate;  Clouded 
Agate. 

QUARTZ  (obscurely  crystalline)  -     157 

Bloodstone,  India;  Tiger-eye,  South  Africa;  Chrysoprase,  Arizona;  Agate  and 
Carnelian,  Lake  Superior;  Jasper,  Germany;  Ribbon  Jasper,  Siberia. 

OPAL    -  -    159 

Precious  Opal  in  matrix,  Queensland;  Precious  Opal,  New  South  Wales; 
Fire  Opal  in  matrix,  Mexico;  Wood  Opal,  Idaho;  Prase  Opal,  Germany. 

TURQUOIS  (New  Mexico)  -     170 

Indian  Amulet;  Waterworn  piece;  Turquois  in  matrix. 


PAGE 

FELDSPAR  -     175 

Amazonstone,  Colorado;  Labradorite,  Labrador;  Moonstone,  Norway;  Sun- 
stone,  Norway. 

MINOR  GEMS    -  -     183 

Chlorastrolite,  Isle  Royale;  Hematite,  England;  Thomsonite,  Lake  Superior; 
Thomsonite,  polished,  Lake  Superior;  Cat's-eye,  Quartz,  Ceylon;  Variscite, 
Utah;  Moldavite,  Bohemia. 

SERPENTINE,  SMITHSONITE,  AND  SATIN  SPAR  -     195 

Serpentine,  Cornwall,  England;  Serpentine,  polished,  Cornwall,  England; 
Smithsonite.  Greece;  Satin  Spar,  Italy;  Thulite,  Norway. 

AMBER,  MALACHITE,  LAPIS  LAZULI,  AND  AZURITE  -  -     205 

Amber,  with  inclosed  insect,  Coast  of  Baltic  Sea;  Amber,  rolled  pebble, 
Coast  of  Baltic  Sea;  Malachite,  Ural  Mountains;  Malachite,  Australia;  Mala- 
chite, Arizona;  Malachite  and  Azurite,  Arizona;  Lapis  Lazuli,  Siberia. 

JADE,  PEARL,  AND  CORAL   -  -  212 

Jade,  variety  jadeite,  Burmah;  Jade,  variety  nephrite,  New  Zealand;  Oriental 
Pearls;  Fresh -water  pearl  grown  to  shell;  Precious  Coral,  Mediterranean 
Sea;  Precious  Coral,  polished;  Chrysoberyl,  Russia. 


PREFACE 

Where  do  they  come  from?  What  are  they  made  of?  How  can 
they  be  distinguished?  What  is  their  value?  —  are  questions  often 
asked  with  regard  to  gems,  the  answers  to  which  must  be  sought 
from  widely  scattered  sources.  In  the  hope  of  affording  means  for 
answering  these  questions  within  concise  and  convenient  limits,  the 
accompanying  work  has  been  prepared.  It  has  been  sought  in  it 
to  avoid  technical  discussions;  but  at  the  same  time  the  use  of  scien- 
tific terms  has  not  been  shunned,  since  they  give  increased  accuracy. 
The  subject  as  a  whole  has  been  treated  from  the  mineralogical  stand- 
point, it  being  believed  by  the  writer  that  this  affords  the  best  basis 
for  a  thorough  knowledge  of  gems.  Each  gem  is  considered  under 
the  mineral  species  to  which  it  belongs;  as,  for  example,  ruby  and 
sapphire  under  corundum;  emerald  and  aquamarine  under  beryl,  etc. 
It  is  probable  that  several  gems  may  not  at  once  be  recognized  under 
this  grouping;  but  on  the  other  hand,  such  an  arrangement  is  likely 
to  lead  to  a  knowledge  of  some  now  little  used. 

In  the  preparation  of  this  book  the  writings  of  others  have  been 
freely  drawn  upon ;  and  in  making  acknowledgment  of  these  the  writer 
would  refer  the  reader  to  them  as  means  of  obtaining  information  upon 
many  points  of  which  the  scope  of  the  present  treatise  has  forbidden 
mention.  * 

First  should  be  mentioned  the  Edelstdnkunde  of  Max  Bauer,  a 
most  elaborate  and  accurate  general  treatise  upon  gems  of  the  present 
day.  Other  useful  general  works  are  Emanuel's  "  Diamonds  and  Precious 
Stones,"  Church's  "Precious  Stones,"  and  Feuchtwanger's  "A  Popular 
Treatise  on  Gems."  Kunz's  "Gems  and  Precious  Stones  of  North 
America"  leaves  nothing  to  be  desired  in  the  treatment  of  this  field; 
and  the  annual  reports  in  the  "  Mineral  Resources  of  the  United  States  " 
by  the  same  indefatigable  worker  serve  to  convey  from  time  to  time  the 
latest  information  upon  gem  matters.  Besides  the  above  mentioned, 
there  are  numerous  works  devoted  to  special  provinces  of  the  study 
of  gems,  which  have  been  and  may  be  consulted  with  profit.  Among 
these  may  be  mentioned  Buffum's  "  The  Tears  of  the  Pleiades ;  "  Shelley's 
" Legends  of  Gems,"  King's  "Antique  Gems,"  Streeter's  "The  Great 


Diamonds  of  the  World,"  Hamlin's  "  Leisure  Hours  among  the  Gems," 
Williams's  "Diamond  Mines  of  South  Africa,"  Boutan's  "Le  Diamant," 
and  Tassin's  "  Descriptive  Catalogue  of  the  Collections  of  Gems  in  the 
United  States  National  Museum,"  1902. 

To  several  individuals  the  writer  is  under  obligations  for  valuable 
assistance.  The  Foote  Mineral  Company  of  Philadelphia  kindly  loaned 
numerous  specimens  for  illustrating  the  colored  plates.  Mr.  Frederick 
J.  Essig,  of  Chicago,  rendered  similar  aid  in  loaning  specimens  of  cut 
stones  and  photographs,  and  also  gave  freely  information  regarding 
many  practical  points. 

To  Dr.  Orville  A.  Derby,  of  the  Geological  Survey  of  Brazil,  Dr.  J.  H. 
Pratt,  Mr.  A.  C.  Lane,  Dr.  A.  C.  Hamlin,  Ernest  Schernikow  and  Prof. 
J.  P.  Iddings  the  writer  is  also  under  obligation  for  the  loan  of  photo- 
graphs ;  and  to  Dr.  P.  Groth,  of  Munich,  for  the  loan  of  a  half-tone  plate. 

Mr.  William  K.  Higley  has  given  the  details  of  preparation  of  the 
plates  and  typographical  execution  of  the  work  much  careful  attention, 
and  the  writer  is  indebted  to  him  for  other  assistance  and  courtesies. 

In  conclusion,  it  is  the  writer's  hope  that  this  work  may  lead  to  a 
wider  knowledge  of  gems,  a  more  intelligent  use  of  them  and  an  admis- 
sion to  their  charmed  circle  of  some  substances  now  shut  out  because 
little  known. 


NATURE  OF  GEMS 

Gems  are  minerals  prized  for  their  color,  hardness,  luster,  and,  for 
the  most  part,  transparency.  It  is  generally  essential  that  a  mineral 
to  be  a  gem  should  excel  in  at  least  three  of  the  above-named  properties, 
although  a  few  are  superior  in  only  two.  Some  minerals  may,  for 
example,  possess  desirable  color  and  luster,  but,  lacking  hardness,  are 
little  used  for  gem  purposes,  because  they  would  become  quickly  marred 
when  worn.  Fluor-spar  is  an  illustration  of  such  a  mineral.  That 
a  high  degree  of  hardness  is  not  essential,  however,  to  the  employment 
of  a  mineral  as  a  gem  is  shown  by  the  extensive  use  of  such  substances 
as  pearl,  amber,  jet,  and  turquois,  for  gems.  All  of  these  are  easily 
scratched  by  ordinary  objects.  It  is  to  be  noted,  however,  that  they  are 
not  transparent  substances,  and  that  an  opaque  or  translucent  substance 
may  endure,  without  serious  injury,  scratches  which  would  be  fatal 
to  the  beauty  of  a  transparent  gem.  Hardness  and  color  alone  cannot, 
however,  make  a  mineral  suitable  for  gem  purposes.  This  fact  is  illus- 
trated by  many  varieties  of  corundum,  which  have  a  high  degree 
of  hardness  and  good  body  color,  but  are  not  used  for  gems  because 
not  transparent.  It  is  evident,  therefore,  that  no  fixed  rule  can 
be  assigned  for  the  use  of  a  mineral  as  a  gem,  the  favor  or  disfavor 
in  which  it  is  held  seeming,  in  many  instances,  to  be  a  matter 
of  pure  caprice. 

But,  however  capricious  popular  favor  may  seem  to  be  in  its  estimate 
of  the  qualities  desirable  in  gems,  it  may  be  set  down  as  a  fairly  general 
rule,  that  the  gems  which  combine  the  most  of  the  qualities  previously 
mentioned  are  those  most  highly  prized.  Thus,  a  red  or  blue  diamond, 
excelling  as  it  does  all  other  minerals  in  hardness  and  luster,  and  being 
the  equal  of  any  in  color  and  transparency,  is  the  most  valuable  of  gems. 
The  ruby  and  sapphire  excel  in  hardness,  and  have  good  color,  luster, 
and  transparency.  They  rank  among  the  most  valuable  of  gems. 

In  speaking  of  minerals  which  have  desirable  gem  qualities,  it  must 
not  be  supposed  that  this  includes  all  occurrences  of  any  particular 
mineral  species.  On  the  contrary,  only  selected  portions  usually  have 
the  desired  qualities.  A  large  part  of  the  yield,  even  of  diamond, 
is  of  no  value  for  gem  purposes,  though  it  all  finds  commercial  use 

i 


on  account  of  its  hardness.  Quartz,  one  of  the  most  abundant  minerals 
of  the  earth's  crust,  though  it  has  the  qualities  of  hardness  and  luster 
suitable  for  a  gem,  can  be  used  only  in  small  quantity  comparatively  for 
gem  purposes,  since  only  few  pieces  have  the  desirable  color  and 
transparency. 

The  selection  of  stones  which  bear  the  qualities  above  mentioned  for 
purposes  of  possession  and  ornament  seems  to  be  a  taste  as  old  as  the 
human  race  itself.  In  the  oldest  Egyptian  tombs  are  to  be  found  necklaces 
containing  emeralds,  garnets,  carnelians,  and  other  precious  stones.  The 
history  of  many  gems  of  India  dates  from  a  period  so  remote  as  to  be 
indeterminate.  The  desire  to  obtain  amber  led  the  Phoenicians  to  make 
some  of  their  earliest  and  longest  voyages.  Gems  were  wrought  into  the 
earliest  ritual  of  the  Hebrews,  and  allusions  to  them  are  frequent 
throughout  their  Scriptures.  The  ancient  Arabs  were  familiar  with 
many  of  the  gems  used  at  the  present  day,  and  ascribed  to  them  special 
qualities.  The  Persian  turquois  mines  are  known  to  have  been  worked 
as  far  back  as  1300  A.D.,  and  probably  much  earlier.  There  is  frequent 
mention  of  gems  by  Greek  writers,  and  the  Romans,  especially  in  the 
later  days  of  the  Empire,  seem  to  have  had  great  fondness  for  jewels, 
and  to  have  sought  them  eagerly  in  their  conquests.  They  used  them 
in  great  variety  and  abundance,  and  carried  the  art  of  cutting  and 
engraving  them  to  a  high  degree  of  perfection. 

Moreover,  gems  are  wrought  into  the  history  and  literature  of  nearly 
all  peoples,  and  furnish  standards  of  color,  hardness,  luster,  etc.,  which 
pass  current  the  world  over.  Such  terms  as  the  "  emerald  meadow," 
"turquois  sky,"  "adamantine  hardness,"  etc.,  are  derived  from  the  use 
of  gems,  and  have  universal  significance.  Advances  in  civilization  seem 
to  increase  rather  than  diminish  the  number  of  minerals  used  as  gems, 
the  number  now  employed  being  larger  than  ever  before  in  the  world's 
history. 

While  it  is  true  that  the  qualities  which  have  been  prized  in  gems, 
and  the  relative  esteem  in  which  they  have  been  held,  seem  to  have 
been  much  the  same  in  all  ages,  the  fashion  in  gems  may  vary  from  time 
to  time,  so  that  now  one  stone  and  now  another  may  take  on  temporarily 
a  higher  value.  Yet,  on  the  whole,  their  worth  varies  little  among 
different  peoples  and  at  different  times.  The  principal  exception  to  this 
rule  is  found  in  the  valuation  of  jade  by  the  Chinese,  for  they  esteem 
this  above  all  other  precious  stones.  Aside  from  a  few  such  exceptions, 
gems  pass  current  in  nearly  all  countries  at  about  the  same  value.  They 
hence  afford  to  a  certain  extent  a  medium  of  exchange,  and  are  often 
made  objects  of  investment,  because  they  are  small,  portable,  and  have 

2 


intrinsic  value.  It  is  not  likely  that  any  great  excess  or  diminution 
of  supply  will  occur  to  change  the  value  of  the  leading  gems,  such 
as  diamond,  ruby,  sapphire,  and  emerald,  as  they  seem  to  be  distributed 
in  the  earth's  crust  in  but  sparing  amount.  Among  the  less  valuable 
gems,  great  variations  in  value  have  occurred,  and  may  again.  Thus 
the  price  of  precious  opal  has  steadily  declined  since  the  discovery 
of  the  Australian  fields,  although  as  fine  gems  are  produced  there 
as  were  ever  known.  Topaz  and  amethyst  have  suffered  a  similar 
decline  in  value,  while  the  price  of  the  gem  known  as  "  tiger  eye  " 
fell  in  a  few  years  from  five  dollars  a  carat  to  twenty -five  cents 
a  pound. 

The  elements  entering  into  the  chemical  composition  of  gems  are 
not  as  a  rule  themselves  rare.  They  are  chiefly  silicon,  aluminum, 
magnesium,  and  other  common  elements,  usually  combined  with  oxygen, 
and  all  abundant  constituents  of  the  earth's  crust.  It  is  thus  not  the 
rarity  of  their  elements  which  gives  gems  their  high  value,  but  rather 
their  peculiar  properties  as  compounds. 

Since  gems  are  unequal  in  value  among  themselves,  many  author- 
ities distinguish  between  gems  and  precious  stones,  and  also  subdi- 
vide the  latter  into  precious  and  semi-precious.  To  the  class  of  gems 
belong,  according  to  such  a  classification,  such  stones  as  the  diamond, 
ruby,  sapphire,  and  emerald;  the  precious  stones  include  amethyst, 
rock  crystal,  garnet,  topaz,  turquois,  moonstone,  opal,  and  the  like; 
and  the  semi  -  precious,  jasper,  agate,  carnelian,  lapis  lazuli,  amazon 
stone,  labradorite,  etc.'"  Since  the  different  kinds  and  qualities  grade 
into  each  other,  insensibly  however,  and  no  sharp  lines  can  be  drawn, 
the  distinction  hardly  seems  worth  making.  In.  tfre  following  pages, 
therefore,  the  terms  gem  and  precious  stone  will  be  used  interchange- 
ably, and  will  be  considered  to  include  any  mineral,  and  even  some 
substances  of  animal  and  vegetable  origin,  which  have  attained  a  cer- 
tain vogue  for  purposes  of  ornament. 


OCCURRENCE   OF   GEMS 

It  was  the  opinion  of  the  ancients  that  gems  were  largely  confined 
in  their  occurrence  to  tropical  countries.  Most  gems  which  they  knew 
were  so  obtained,  India  being  the  chief  source  of  them.  Their  wise 
men  reasoned,  therefore,  that  the  warmth  and  light  of  the  sun  of  the 
tropical  zone  were  needed  to  give  gems  that  fire  and  brilliancy  which 
made  them  precious  among  stones.  With  the  wider  knowledge  of  the 
earth  which  has  been  gained  in  later  times,  however,  it  has  become  evi- 
dent that  climatic  conditions  have  little  or  nothing  to  do  with  the 
occurrence  of  gems.  The  greater  oxidation  produced  by  the  heat  of  the 
sun  in  the  tropics  may  add  to  the  warmth  of  color  of  such  stones  as 
the  carnelian  and  agate,  but  it  would  have  a  tendency  to  fade  the 
amethyst  and  sapphire.  A  greater  abundance  of  gems  in  the  tropics 
may  arise  from  more  extensive  decomposition  of  the  rocks  there,  and 
this  is  undoubtedly  a  favorable  circumstance.  Moreover,  glaciated  coun- 
tries, such  as  the  northeastern  portion  of  North  America,  have  a  soil 
composed  of  too  heterogeneous  a  mixture  to  favor  the  search  for  gems. 
So  far  as  the  underlying  rock  is  concerned,  however,  there  is  not,  so  far 
as  we  know  at  present,  any  distribution  by  latitudes  which  favors  one 
locality  over  another.  Hence  the  mountain  fastnesses  of  the  Urals 
furnish  gems  no  less  than  the  broad  valleys  of  India,  the  bleak  shores 
of  Labrador  as  well  as  the  steaming  jungles  of  Burmah,  and  the 
barren  veldt  of  the  Transvaal  as  well  as  the  thickly  settled  valleys 
of  Bohemia. 

The  first  discovery  of  gems  in  a  region  is  usually  made,  like  that 
of  gold,  in  the  beds  of  streams.  Often  it  is  in  the  search  for  gold  that 
gems  are  found,  as  is  illustrated  by  the  fact  that  the  discoveries  of  diamonds 
in  Brazil,  sapphires  in  Montana,  and  rubies  in  North  Carolina  were  made 
in  this  manner. 

The  frequent  occurrence  of  gems  in  the  beds  of  streams  is  due  to  the 
fact  that  the  gem  minerals  are  usually  harder  and  less  easily  decom- 
posed than  the  other  minerals  of  the  rocks  in  which  they  were  formed. 
Hence  they  remain  after  the  mother  rock  has  disintegrated  and  its  con- 
stituents for  the  most  part  removed.  The  discovery  of  gems  in  a  stream 
bed  is  further  facilitated  by  the  enhancing  of  their  color  when  wet, 

4 


causing  them  to  attract  attention.  Moreover,  the  flowing  stream  tends 
to  group  together  minerals  of  the  same  specific  gravity,  thus  causing 
a  concentration  of  the  gem  minerals.  A  stream  bed  is  therefore  a  good 
place  to  look  for  gems.  Besides  the  fact  that  the  gems  are  concentrated 
here,  and  can  more  easily  be  seen,  a  further  advantage  lies  in  the 
fact  that  they  are  likely  to  be  of  better  quality  than  those  found  in 
the  matrix,  since  the  wear  of  the  stream  has  opened  and  separated 
them  along  any  little  seams  that  may  have  existed,  and  the  pieces 
left  will  be  of  uniform  texture  and  free  from  imperfections.  On  the 
other  hand,  a  continual  reduction  in  size  takes  place  from  the  wear 
of  the  stream,  and  larger  gems  will  therefore  be  obtained  by  search- 
ing the  mother  rock.  The  quantity  of  any  given  gem  is  likely,  too, 
to  be  limited  in  a  stream  deposit  as  compared  with  the  deposit  in 
place ;  and  just  as  with  gold,  the  mother  lode  must  eventually  be  sought 
if  a  permanent  supply  is  desired. 

It  must  not  be  supposed,  however,  in  speaking  of  stream-bed  deposits, 
or  "  gravels,"  as  they  are  usually  called,  that  only  gravels  over  which 
water  is  now  flowing  are  meant.  Beds  of  earlier  streams  will  afford 
the  same  products  and  the  same  facilities,  with  the  exception  that 
the  color  of  the  precious  stones  will  not  be  so  obvious.  It  is  evident, 
too,  that  in  any  particular  gravel  the  quantity,  size,  and  variety  of  the 
gem  minerals  present  will  depend  not  only  on  their  quantity  and  variety 
in  the  original  rock  mass  of  which  they  formed  a  part,  but  on  the 
length  of  time  they  have  been  exposed  to  wear  and  the  rate  of  flow 
of  the  stream. 

In  the  so-called  gem  gravels,  numbers  of  gem  minerals  are  usually 
associated  together.  Thus,  in  those  of  Ceylon  are  to  be  found  sapphire, 
tourmaline,  zircon,  garnet,  spinel,  iolite,  and  many  others;  and  in  those 
of  Brazil,  topaz,  chrysoberyl,  andalusite,  and  others.  Quartz,  garnet, 
and  beryl  are  frequent  constituents  of  gem  gravels,  as  well  as  the 
heavier  minerals  ilmenite,  rutile,  and  magnetite.  The  knowledge  that 
garnets  usually  accompanied  diamonds  in  the  "  wet  diggings "  along 
the  Vaal  River  led  to  the  discovery  of  the  "  dry  diggings  "  at  Faure- 
smith,  in  South  Africa,  and  in  other  cases  a  knowledge  of  the  min- 
erals usually  associated  with  a  gem  has  been  of  great  aid  in  discover- 
ing the  gem  itself.  This  grouping  together  of  the  gem  minerals  arises 
from  the  fact  that  they  are  not  only  formed  together  in  the  original 
rock  mass,  but  also  that  they  are  of  about  the  same  hardness,  and 
to  a  certain  extent,  specific  gravity. 

The  beaches  of  lakes,  or  of  the  sea,  also  afford  places  for  the  gather- 
ing of  gems  by  processes  similar  to  those  just  described.  By  wave 

5 


action  and  currents  the  cliffs  of  the  shore  are  continually  being  worn 
down,  and  the  lighter  and  finer  particles  borne  sea-ward,  while  those 
which  are  heavier,  either  because  of  higher  specific  gravity,  or  of  greater 
resistance  to  erosion  and  decomposition,  and  hence  larger,  remain  behind. 
A  continual  concentration  is  thus  going  on  which  in  time  may  pro- 
duce gem  deposits  of  some  extent.  The  area  upon  which  such  a  depo- 
sition may  take  place  is,  however,  relatively  narrow  at  any  one  period, 
as  compared  with  that  afforded  by  streams,  and  hence  few  gems  are 
likely  to  be  obtained  from  such  sources.  Labradorite  and  hypersthene 
are  obtained  from  deposits  of  this  character  upon  the  coast  of  Labrador; 
chlorastrolite  from  the  shore  of  Isle  Royale ;  and  agate  and  thomsonite 
from  beaches  of  Lake  Superior.  Hardly  any  other  gem  minerals  can 
be  mentioned  as  so  obtained,  with  the  exception  of  amber,  which  is 
gathered  from  the  coast  of  the  Baltic  Sea.  This,  however,  is  deposited 
not  through  its  heaviness  but  its  lightness,  it  being  borne  upon  the 
waves  and  tossed  inland. 

Passing  from  the  gravels  in  which  gems  are  found  to  a  consideration 
of  their  original  rock  matrices,  it  may  be  said  that  rocks  of  the  kind 
known  as  metamorphic  are  more  commonly  than  any  others  the  home 
of  the  gem  minerals.  Metamorphic  rocks  are  those  which  have  been 
changed  by  heat  and  pressure,  or  chemical  agencies,  from  their  original 
condition.  They  include  crystalline  limestones,  quartzites,  mica  and 
hornblende  schists,  gneisses,  eclogites,  etc.  The  rubies  of  Burmah,  the 
emeralds  of  the  Urals,  the  diamonds  of  Brazil  and  the  garnets  of  the 
Alps  are  illustrations  of  gems  which  occur  in  this  way. 

Next  to  metamorphic  rocks  those  of  an  eruptive  character  afford 
the  gem  minerals  in  the  greatest  abundance.  Of  these  the  acidic 
rocks,  i.  e.,  those  containing  a  relatively  large  quantity  of  silica,  such 
as  the  granites,  trachytes,  rhyolites,  and  syenites,  are  the  most  prolific. 
The  coarsely  crystallized  form  of  granite  known  as  pegmatite  is  espe- 
cially fertile  in  the  gem  minerals.  The  basic  eruptive  rocks,  i.  e.,  those 
poor  in  silica,  afford  among  gem  minerals,  chrysolite,  some  garnet, 
some  corundum,  vesuvianite,  and  a  few  others.  They  are,  however, 
comparatively  barren.  The  diamonds  of  South  Africa  occur  in  a  rock 
seeming  to  be  of  a  basic  eruptive  character ;  but  whether  the  diamonds 
are  of  primary  or  secondary  origin  is  not  yet  known. 

Of  all  the  great  groups  of  rocks  those  of  sedimentary  origin  furnish 
the  fewest  gems.  Those  which  do  occur  in  these  are  for  the  most 
part  probably  derived  from  older  eruptive  rocks.  Such  is  believed  to  be 
the  origin  of  the  emeralds  of  Colombia,  which  are  found  in  a  bitumi- 
nous limestone  of  Cretaceous  age.  The  opals  of  New  South  Wales,  how- 

6 


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ever,  occurring  in  sandstones  and  limestones  of  Tertiary  age,  doubtless 
were  formed  in  place,  and  owe  their  deposition  to  the  circulation 
of  siliceous  waters  through  the  rocks. 

The  distribution  of  gems  through  a  rock  or  gravel  matrix  is  not 
usually  uniform.  The  gems  more  commonly  occur  in  pockets,  so  called, 
the  location  of  which  seems  to  be  governed  by  no  law  as  yet  dis- 
covered. Where  crystallization  of  minerals  has  taken  place  about 
a  fissure  or  open  cavity,  the  minerals  are  more  likely  to  be  clear 
and  free  from  inclusions  than  where  formed  in  the  mass  of  the  rock 
itself. 


MINING  OF   GEMS 

The  methods  employed  in  the  mining  of  gems  depend  obviously 
upon  the  occurrence  of  the  latter.  If  occurring  in  gravels,  or  decom- 
posed rock  areas,  as  is  the  case  with  the  majority  of  gems,  mining 
usually  takes  the  form  of  open  cuts,  made  either  by  digging  numerous 
small  pits,  or  one  of  extensive  dimensions.  The  separation  of  the 
gems  from  the  common  pebbles  accompanying  them  is  then  performed 
by  some  method  of  washing,  usually  hand  panning  combined  with  hand 
picking.  Panning  depends  for  its  operation  upon  the  generally  high 
specific  gravity  of  the  gem  minerals  as  compared  with  those  of  com- 
moner occurrence,  and  is  thus  similar  in  principle  to  gold  panning. 
The  utensil  most  commonly  employed  is  a  shallow  pan  of  wood  or 
metal,  from  12  to  18  inches  in  diameter,  and  of  a  more  or  less  coni- 
cal shape.  On  taking  up  a  quantity  of  the  gem-bearing  gravel  in  this 
with  water,  and  rinsing  the  whole  with  a  circular  motion,  the  lighter 
minerals  fly  off  and  the  heavier  concentrate  toward  the  center.  After 
the  contents  of  the  pan  have  in  this  manner  been  considerably  reduced, 
by  searching  and  hand  picking  any  gems  which  may  have  gathered 
at  the  center  can  usually  be  readily  seen  and  picked  out. 

Of  the  methods  of  mining  and  separating  gravels  by  hand  digging 
and  panning,  the  procedure  of  the  Cingalese  in  exploiting  the  Ceylon 
gem  gravels  may  be  considered  a  good  illustration.  These  methods 
are  thus  described  by  Dr.  A.  C.  Hamlin : 

"The  mining  operations  are  generally  carried  on  by  the  native 
Cingalese,  who  labor  in  the  light  of  a  pastime,  and  only  during  inter- 
vals of  their  agricultural  employments.  Some  few,  however,  undertake 
the  labor  as  a  regular  business,  but  they  belong  to  a  low  and  dissipated 
class,  and  do  not  work  systematically  or  with  regularity.  Therefore, 
the  gem -mining  of  Ceylon  cannot  be  regarded  as  a  fixed  and  per- 
manent business. 

"When  an  exploration  has  been  determined  upon,  a  small  party 
of  villagers  set  out  for  the  promising  region  provided  with  the  imple- 
ments of  mining  and  the  means  of  camping  out.  The  times  selected 
for  the  operations  are  after  the  heavy  rains,  which  prevail  in  June  and 
October,  and  the  floods  have  subsided.  The  beds  of  rivers,  or  smaller 

8 


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streams,  are  often  chosen  as  easier  of  access  than  the  plains.  If  the 
river-bed  is  selected,  the  first  act  of  the  explorers  is  to  seek  for  the 
proper  locality  where  the  gem-bearing  strata  may  be  found.  To  ascer- 
tain this,  the  Cingalese  thrust  a  long  iron  rod  of  ten  or  twelve  feet 
in  length  into  the  earth,  and  test  the  nature  of  the  sub-soil.  By  means 
of  long  practice  the  natives  can  adroitly  penetrate  the  earth  to  a  con- 
siderable depth;  and,  by  the  resistance  to  the  movement  of  the  rod, 
can  detect  the  gem  deposit  of  which  they  are  in  search. 

"If  the  indications  are  good,  the  natives  proceed  to  build  a  hut 
if  they  are  at  a  distance  from  their  village,  and  prepare  for  the  oper- 
ations, which  often  extend  over  many  weeks.  After  diverting  a  part 
of  the  force  of  the  stream  so  as  to  form  a  quiet  pool,  they  proceed 
to  excavate  the  sand  and  gravel  within  a  certain  area.  In  order 
to  accomplish  this  they  use  hoes  with  handles  fifteen  or  more  feet  in 
length.  The  top  strata  are  hurriedly  raked  up  and  thrown  away; 
but  as  the  pit  deepens  and  the  gem  stratum  is  approached,  the  work 
is  performed  with  greater  care.  As  soon  as  the  hoes  bring  up  frag- 
ments and  boulders  of  white  quartz,  or  strike  thin  ferruginous  crust, 
every  particle  of  the  gravel  drawn  up  is  carefully  preserved.  The 
gravel  and  sand  thus  obtained  are  then  placed  in  large  baskets  woven 
of  split  bamboo  and  shaped  to  a  conical  point  at  the  bottom.  The 
basket  thus  filled  is  placed  in  the  current  of  water,  and  its  contents 
washed  by  imparting  to  it  a  circular  motion.  This  washing  process 
is  kept  up  until  the  stones,  gravel,  and  lesser  particles  are  cleansed. 
During  this  operation  the  gems,  which  are  much  heavier  than  com- 
mon stones,  settle  at  the  bottom  of  the  basket,  and  are  there  collected 
together,  so  that  when  the  superincumbent  gravel  is  removed,  the 
sapphires,  garnets,  zircons,  etc.,  are  easily  discovered  at  the  bottom 
and  removed.  This  is  the  manner  in  which  the  wet  diggings  are 
carried  on,  and  is  the  easiest  mode  of  exploration;  but  it  is  by  no 
means  as  sure,  or  often  as  profitable,  as  the  operations  in  dry  ground 
on  the  river  banks  or  in  the  plains.  The  dry  diggings  are  much  more 
laborious,  as  the  soil  is  firmer,  and  the  gem  strata  must  be  trans- 
ported to  water  to  be  washed  and  sifted.  These  dry  deposits  are 
found  the  richest  beneath  the  alluvial  plains,  which  seem  to  have 
been  in  distant  times  shallow  lakes  and  lagoons. 

"  The  gem  stratum,  called  mellan,  is  always  well  defined,  and  occurs 
at  a  certain  depth,  which  seems  to  correspond  to  the  bottom  of  the 
lake  at  a  definite  period.  This  depth  varies  from  two  to  twenty  feet, 
and  is  perhaps  even  greater;  but  the  natives  rarely  excavate  below 
the  depth  of  twenty  feet.  This  peculiar  formation,  which  is  generally 


horizontal,  is  composed  of  a  conglomerate  of  quartz  gravel  resting  upon 
or  mixed  with  a  stiff  clay,  often  indurated  by  a  ferruginous  oxide.  In 
among  this  cascalho,  or  just  below  it  and  adhering  to  it,  are  found 
the  fine  pebbles  and  crystals  of  sapphire,  tourmaline,  garnet,  zircon, 
spinel,  and  chrysoberyl.  Under  these  rocks,  and  in  peculiar  hollows 
in  the  plastic  clay,  which  the  natives  call  '  elephants'  footsteps,'  the 
gems  are  found  clustered  together  heterogeneously,  and  often  so  per- 
fect in  form  as  to  appear  as  though  created  there.  At  other  places 
they  are  collected  together  in  these  pockets,  in  such  a  manner  as  to  sug- 
gest the  idea  that  they  had  been  washed  in  by  a  current  of  water." 

An  account  of  the  methods  of  gem  mining  in  Brazil,  which  in  many 
respects  are  similar  to  those  above  described,  will  be  found  in  the 
chapter  on  the  Diamond  in  this  work.  Such  methods  may  be  con- 
sidered typical  of  the  mining  of  gems  on  a  small  scale.  Their  success 
will  obviously  largely  depend  upon  the  skill  and  care  of  the  individual 
miner.  In  countries  where  hand  labor  is  cheap  such  methods  can 
usually  be  conducted  with  better  profit  than  can  be  afforded  by  the 
use  of  machinery.  This  will  especially  be  true  if  the  gem  deposits 
are,  as  is  often  the  case,  scattered  over  a  wide  area  and  are  irregular 
in  quantity. 

The  part  of  the  operation  of  gem  mining  to  which  some  form 
of  machinery  or  apparatus  can  usually  be  most  profitably  applied, 
is  that  of  washing  or  concentration. 

The  machines  employed  for  this  purpose  may  vary  from  the  crude 
"baby"  of  the  South  African  Vaal  River  miner  to  the  elaborate  jigs 
and  pulsators  of  the  Kimberley  mines. 

Most  of  these  methods  are  patterned  after  those  of  gold  placer  min- 
ing, and  depend  for  their  success  upon  the  same  principle. 

The  mining  of  sapphires  in  Montana  affords  an  illustration  of  a  com- 
bination of  several  methods  of  washing,  which  typifies  what  may  be  done 
in  this  manner.  It  is  thus  described  by  Mr.  George  F.  Kunz  in  the 
Mineral  Resources  of  the  United  States  for  1901 : 

"The  methods  employed  are  a  curious  combination  of  those  of  the 
California  gold-workings  and  the  South  African  diamond  mines.  As  in 
the  latter,  the  gangue  of  the  gems  is  an  igneous  rock,  hard  below 
but  decomposed  above,  in  varying  degrees,  to  a  mere  earthy  mass 
at  the  surface.  From  this  last  the  gems  are  separated  by  washing 
and  sluicing,  much  in  the  manner  of  placer  gold;  though,  because 
of  the  less  density  of  sapphires,  more  care  is  necessary,  and  the  sluice 
boxes  must  be  less  inclined,  to  prevent  the  gems  from  being  carried 
over  the  riffles.  Most  of  the  New  Mine  Syndicate's  workings  are  sur- 

10 


face  openings  and  cuts,  some  of  the  latter  very  extensive.  Water 
is  carried  from  Yogo  Creek,  ten  miles  distant,  by  a  ditch  and  flume, 
with  a  parallel  hydraulic  pipe  line;  and  a  system  of  sluices  extends 
all  along  the  company's  workings. 

"Where  the  rock  is  much  decomposed,  the  hydraulic  process  is 
employed  largely;  as  it  becomes  harder,  power  is  necessary  to  break 
it  up.  Then  the  rock  is  thrown  out  in  dumps  and  allowed  to  disin- 
tegrate by  exposure  to  the  weather,  as  with  the  African  "hard  blue." 
This  process  requires  from  a  month  to  a  year,  according  to  the  con- 
dition of  the  material.  Sometimes  a  stream  of  water  is  turned  on 
the  dumped  rock,  and  the  process  thus  expedited.  When  sufficiently 
decomposed,  this  material  is  subjected  to  the  same  washing  process 
as  the  material  naturally  disintegrated. 

"In  the  washing  the  fine  earth  is  carried  away  with  the  water; 
all  hard  lumps  remaining  are  again  thrown  out  on  a  dump  to  decom- 
pose further;  and  the  sapphires,  after  several  screenings,  are  picked 
out  by  hand." 

An  interesting  discovery  made  in  South  Africa,  in  connection  with 
the  process  of  sorting  diamonds  by  concentrating  them  on  percussion 
tables,  was  that  if  the  tables  were  covered  with  thick  grease  the 
diamonds,  and  even  other  precious  stones,  such  as  rubies,  sapphires, 
and  emeralds,  would  adhere  to  the  grease  and  be  held,  while  the  value- 
less ingredients  of  the  rock  would  pass  by.  The  grease  can  be  used  for 
this  purpose  for  only  a  few  hours  when  it  must  be  scraped  off  and  a 
new  coat  applied.  This,  however,  is  a  small  disadvantage  compared 
with  the  great  gain  afforded  by  the  selective  power  of  the  "  greaser," 
as  it  is  called. 

Mining  for  gems  by  methods  of  tunneling,  shafts,  and  other  means 
employed  in  deep  mine  workings  is  rarely  carried  on.  In  the  first 
place,  gems  do  not  often  occur  in  definite  veins  as  do  the  precious 
metals,  being  more  commonly  irregularly  distributed  in  pockets  through 
the  rock.  In  the  second  place,  little  really  systematic  mining  of  gems 
is  carried  on.  As  a  rule,  the  occupation  is,  or  has  been,  a  rather  desul- 
tory one.  A  find  of  a  few  good  stones  leads  to  temporary  search  and 
exploration,  lasting  for  a  few  years  perhaps,  then  the  work  proves  no 
longer  profitable  and  is  abandoned  until  new  finds  arouse  *  new  hope 
and  revive  the  industry. 

The  element  of  fortune,  good  and  bad,  seems  to  prevail  more  largely 
in  the  mining  of  gems  than  in  even  that  of  the  precious  metals.  In 
gem-mining,  as  in  that  for  gold  and  silver,  great  labor  and  little  reward 
go  side  by  side  with  little  labor  and  great  reward.  Moreover,  the  dis- 

11 


tribution  of  gems  is  exceedingly  irregular,  and  their  market  price  varies 
within  wide  margins,  from  circumstances  of  fashion,  supply,  general 
financial  conditions,  etc. 

Yet  these  contingencies  might  doubtless  be  largely  overcome  by 
intelligent  and  broad-minded  management,  such  as  has  been  conspicu- 
ously displayed  in  the  conduct  of  the  diamond  mines  of  South  Africa. 
Not  only  is  the  mining  here  conducted  according  to  the  most  approved 
systems  of  modern  engineering,  but  equal  attention  is  paid  to  placing 
the  gems  upon  the  market,  so  that  an  over-supply  shall  not  reduce  the 
price.  Some  further  account  of  this  will  be  found  in  the  chapter  on 
the  Diamond. 

Regarding  the  influence  of  increase  of  depth  upon  the  distribution 
and  quality  of  the  gem  minerals,  no  principles  have  been  established 
as  yet.  It  is  known  that  veins  of  amethysts,  for  instance,  have  turned 
entirely  colorless  on  penetrating  below  the  surface,  so  that  a  valuable 
stone  became  with  depth  worthless.  On  the  other  hand,  improvement 
in  color  and  quality  of  stones  below  the  surface,  as  compared  with 
those  above,  may  often  be  reasonably  expected,  since  the  latter  are 
more  exposed  to  disintegration  and  weathering,  and  the  fading  effects 
of  light. 

In  the  mining  of  gems  in  a  small  way  the  amateur  is  likely  to  make 
the  mistake  of  resorting  to  the  use  of  too  much  powder  or  other 
explosive.  While  the  rough  work  of  exploration  may  wisely  be  carried 
on  by  means  of  blasting,  the  actual  removal  of  the  mineral  from  the 
matrix  should  usually  be  performed,  where  possible,  by  picks  and  chisels, 
in  order  to  avoid  the  shattering  and  breaking  of  pieces  suitable  for  gems, 
which  often  happens  in  blasting.  Many  fine  gems  have  been  lost  through 
carelessness  in  the  work  of  mining,  and  while  not  all  losses  of  this  kind 
can  be  avoided,  with  care  and  patience  they  can  be  reduced  to  a  mini- 
mum. 


12 


COLOR  OF  GEMS 

The  color  of  gems  is  one  of  the  most  essential  features  of  their  value. 
While  certain  colorless  gems,  such  as  the  diamond,  are  highly  prized, 
even  the  diamond  would  lose  much  of  its  value  if  it  did  not  flash 
colored  lights.  So  the  quality  of  affording  a  permanent  color  probably 
leads  to  much  of  the  esteem  in  which  gems  are  held.  The  colors 
of  the  rose  and  the  violet  are  not  less  pleasing  than  those  of  the  ruby 
and  amethyst,  but  the  former  endure  but  for  a  day  while  the  latter  can 
be  handed  down  unimpaired  from  generation  to  generation.  It  was  prob- 
ably to  secure  varieties  of  color  that  the  ancients  first  used  gems,  for 
their  classifications  and  designations  of  precious  stones  were  based  chiefly 
upon  this  property.  With  them  almost  any  green  stone  was  known  as 
emerald,  blue  as  sapphire,  and  red  as  ruby  or  carnelian.  This  fact  makes  it 
difficult  in  reading  accounts  of  gems  as  given  by  ancient  authors  to  know 
what  mineral  is  meant.  Distinctions  of  hardness  and  specific  gravity, 
now  so  much  in  use,  seem  to  have  been  ignored  by  them  for  the  most 
part.  With  the  grouping  of  minerals  according  to  their  chemical  com- 
position, the  significance  of  color  largely  disappeared  as  a  means  of 
distinction,  since  individual  specimens  of  the  same  composition,  and 
hence  the  same  species,  may  vary  greatly  in  color.  Usually  the  quantity 
of  ingredient  required  to  produce  a  certain  color  is  too  small  to  be  detected 
by  chemical  analysis.  That  the  custom  of  distinguishing  gems  by  their 
colors  still  survives,  however,  to  a  considerable  extent,  is  evidenced  by  the 
fact  that  different  names  are  still  applied  to  gems  of  the  same  mineral 
when  of  different  colors.  Thus  sapphire  and  ruby  are  both  corundum ; 
and  emerald  and  aquamarine  are  beryl.  The  mineral  quartz  appears  in 
a  multitude  of  colors,  to  nearly  all  of  which  different  names  are  given. 
Hence  gems  of  two  different  names  may  occur  even  in  the  same  crystal : 
as  in  a  piece  of  quartz,  from  one  portion  an  amethyst  may  be  cut  and 
from  another  a  citrine.  On  the  other  hand,  different  species  may  pre- 
sent stones  of  exactly  the  same  color.  Thus  corundum,  spinel  and  garnet 
all  afford  red  stones,  often  nearly  alike  in  tint ;  or  emerald  and  tourma- 
line both  give  green  stones.  Speaking  from  the  mineralogical  stand- 
point, there  are  few  minerals  and  fewer  gems  in  which  color  is  a  constant 
and  essential  property.  Those  which  may  be  mentioned  as  belonging  to 

13 


the  latter  class  are  pvjite,  which  is  biass  yellow,  lapis  lazuli,  which  is 
blue,  and  malachite,  which  is  green. 

In  a  few  cases  differences  of  chemical  composition  are  indicated  by 
differences  of  color.  This  is  true  of  garnet,  the  magnesium -aluminum 
varieties  of  which  are  ruby  red,  the  calcium-aluminum  varieties  brownish 
red,  and  the  calcium-chromium  varieties  green.  So  tourmaline,  when 
containing  an  excess  of  iron,  is  black ;  an  excess  of  sodium  and  lithium 
is  green  or  red,  and  an  excess  of  magnesium  is  brown. 

Usually,  however,  the  coloring  matter  is  foreign  to  the  essential  com- 
position of  the  mineral,  and  of  very  small  amount. 

This  coloring  ingredient  is  in  the  majority  of  cases  organic  matter  of 
some  sort,  chiefly  hydrocarbons.  This  has  been  proved  in  some  cases  by 
analysis,  and  in  general  may  be  assumed  when  the  color  of  a  stone  can 
be  driven  out  or  changed  by  heat.  The  following  gems  quite  certainly 
owe  their  color  wholly  or  in  part  to  organic  matter: — smoky  quartz, 
amethyst,  yellow  topaz,  golden  beryl,  zircon,  rubellite,  and  amazon  stone. 
The  coloring  ingredients  of  the  following  are  chiefly  inorganic : — ruby, 
sapphire,  spinel,  and  emerald. 

Next  to  organic  matter  metallic  oxides  are  probably  the  most  preva- 
lent coloring  ingredient.  These  oxides  may  occur  in  scales  large  enough 
to  be  seen  with  the  naked  eye,  as  is  true  of  the  hematite  in  sunstone,  or 
they  may  be  only  visible  with  the  microscope,  as  the  same  substance  can 
be  seen  coloring  jasper  and  carnelian.  More  commonly  the  coloring  mat- 
ter cannot  be  discerned  as  a  distinct  pigment.  Beside  oxide  of  iron  as  a 
coloring  ingredient,  chromium,  copper  and  nickel  oxides  occur,  producing 
in  general  green  colors.  Manganese  oxide  often  gives  purple  or  flesh  colors. 

By  producing  some  chemical  change  it  is  often  possible  to  alter  the 
color  of  a  mineral.  In  the  case  of  minerals  colored  by  hydrocarbons, 
these  changes  may  best  be  produced  by  heating.  In  this  manner  smoky 
quartz  can  be  changed  in  color  to  yellow,  yellow  topaz  to  pink,  and 
brown  carnelian  to  red. 

Amethyst,  hyacinth,  and  golden  beryl  lose  their  color  entirely  if  heated 
any  length  of  time,  and  smoky  quartz  may  also  be  made  colorless  by 
long  continued  heat.  Some  gems  change  in  color  on  heating,  but  regain 
it  again  when  cooled.  Thus  pyrope  turns  darker  on  heating,  but  returns 
to  its  normal  color  on  cooling.  Ruby  becomes  colorless,  but  on  cooling 
changes  through  green  to  its  original  red. 

Some  colors  of  gems  fade  or  change  on  exposure  to  light,  a  peculiarity 
which  is  of  course  considered  detrimental  to  their  value.  In  this  manner 
the  blue  of  turquois  may  change  in  time  to  green,  and  yellow  topaz, 
chrysoprase,  and  rose  quartz  may  lose  their  color  entirely. 

14 


Some  gems  are  of  a  different  color  by  artificial  as  compared  with  day 
light.  The  beauty  of  some  may  thus  be  enhanced  by  artificial  light  and 
that  of  others  weakened.  The  gem  in  which  the  most  striking  change  is 
thus  produced  is  chrysoberyl  of  the  variety  known  as  alexandrite.  This  is 
green  by  daylight,  but  red  by  artificial  light.  Most  yellow  stones  appear 
nearly  colorless  by  artificial  light  because  the  excess  of  yellow  rays  in  the 
latter  makes  those  from  the  stone  almost  invisible.  For  the  same  reason 
violet  stones  are  likely  to  lose  much  of  their  color  in  artificial  light. 
One  of  the  points  of  superiority  of  the  emerald  is  that  it  is  able  to  retain 
its  color  in  all  lights.  The  color  of  the  ruby  is  deepened  and  made  more 
brilliant  by  artificial  light,  and  turquois  of  good  color  has  its  effect 
enhanced  by  the  same. 

LIST  OF  GEMS  ACCORDING  TO  COLORS. 


Black. 
Diamond. 
Tourmaline. 
Garnet. 
Quartz. 
Jet. 

Gadolinite,  Samarskite,  etc. 
Blue. 
Diamond. 
Sapphire. 

Tourmaline  (Indicolite.) 
Topaz. 
Beryl, 
lolite. 
Turquois. 
Lapis  Lazuli. 
Brown. 
Diamond. 
Hyacinth. 
Garnet. 
Tourmaline. 
Quartz  (Smoky). 
Andalusite. 
Green. 
'  Diamond. 
Emerald. 

Oriental  Emerald. 
Peridot. 
Chrysoberyl. 
Tourmaline. 
Dioptase. 


Green  (continued). 
"Topaz. 
Garnet. 
Aquamarine. 
Euclase. 
Hiddenite. 
Malachite. 
Variscite. 
Nephrite. 
Chrysoprase. 
Heliotrope. 
Plasma. 
Pink. 
Diamond. 
Spinel. 
Ruby. 
Beryl. 

Topaz  (heated). 
Tourmaline. 
Red. 

Diamond. 
Ruby. 
Spinel. 
Garnet. 
Tourmaline. 
Rhodonite. 
Fire  Opal. 
Carnelian. 
Jasper. 


15 


Violet. 

Diamond. 

Amethyst. 

Sapphire. 

Spinel. 

White. 


Jade. 

Yellow. 

•  Diamond. 
Topaz. 
•Chrysolite. 

•Corundum  (Oriental  topaz). 

Spinel. 
•Beryl. 
•Amber. 
•Chrysoberyl. 

Garnet. 

Hyacinth. 

•  Quartz  (Citrine). 
Colorless. 

'Diamond. 
Zircon. 

•  Corundum. 
•Beryl. 
"Topaz. 
•Rock  Crystal. 

•  Tourmaline. 

TtilPCOH  * 

•  Spinel. 

•  Phenacite. 


LUSTER 

The  luster  of  gems  is  one  of  their  important  and  distinctive  char- 
acters. Not  only  does  it  form  one  of  the  easiest  means  of  distinguish- 
ing gems,  but  it  is  also  one  of  the  most  reliable  characters  sought  by 
those  experts  who  depend  for  their  determinations  of  gems  on  ocular 
examination  alone.  One  familiar  with  the  luster  of  quartz,  as  com- 
pared with  that  of  diamond,  for  example,  is  in  little  danger  of 
confusing  the  two,  for  the  luster  of  one  can  be  recognized  as 
adamantine,  that  of  the  other  as  vitreous.  The  luster  of  a  gem  is  pro- 
duced by  the  light  which  it  reflects  back  to  the  eye,  and  this  may 
vary  in  quantity  and  quality  with  the  nature  of  the  surface.  Since  the 
latter  is  largely  the  result  of  the  molecular  structure  of  the  mineral, 
it  follows  that  different  species  will  have  distinctive  luster.  The  terms 
used  to  describe  the  different  kinds  of  luster  are  derived  from  that 
afforded  by  some  well-known  object.  Thus  adamantine  luster  means 
the  luster  of  the  diamond;  vitreous  luster,  the  luster  of  broken  glass; 
oily  luster,  the  luster  of  oil;  waxy  luster,  the  luster  of  wax;  resinous 
luster,  the  luster  of  resins ;  pearly  luster,  the  luster  of  pearl ;  silky  luster, 
the  luster  of  silk ;  and  metallic  luster,  the  luster  of  shining  metals. 

Of  the  above  kinds  of  luster,  the  vitreous  is  the  most  common  among 
gems,  being  displayed  by  quartz,  topaz,  beryl,  tourmaline,  sapphire,  and 
many  others.  The  adamantine  luster  belongs  almost  exclusively  to  the 
diamond,  although  it  is  displayed  to  some  extent  by  sphene  and  color- 
less zircon  and  is  suggested  by  some  sapphire.  It  is  characteristic 
of  minerals  of  a  high  index  of  refraction.  Metallic  luster  is  strictly 
possessed  only  by  opaque  minerals,  and  hence  among  gems  is  confined 
to  pyrite  and  hematite.  The  luster  of  turquois  is  of  the  waxy  order. 
Essonite  displays  a  somewhat  resinous  luster,  and  chrysolite  an  oily 
one.  Pearly  luster  is  best  seen  in  the  pearl,  but  is  also  illustrated 
by  moonstone  and  opal.  Tiger  eye  and  cat's  eye  afford  examples 
of  silky  luster. 


16 


HARDNESS 

Tests  of  hardness  afford  one  of  the  most  useful  and  convenient  means 
of  distinguishing  gems.  Such  tests  can  be  easily  made  and  are  very 
reliable,  the  hardness  of  species  being  remarkably  constant.  Hardness 
should  not,  however,  be  confounded  with  toughness,  i.  e.,  the  difficulty 
with  which  a  mineral  can  be  broken,  since  many  brittle  minerals  have 
considerable  hardness.  Hardness  is  rather  the  power  of  resistance  to 
scratching  which  a  mineral  possesses. 

It  is  evident  that  a  high  degree  of  hardness  must  be  an  important 
property  of  precious  stones,  as  their  polish  would  soon  disappear  if  they 
were  easily  scratched. 

The  common  method  of  stating  the  hardness  of  a  mineral  is  by 
referring  it  to  its  place  in  the  scale  devised  by  the  German  mineralo- 
gist Mohs.  The  divisions  of  this  scale  are  constituted  by  ten  rather 
common  minerals,  arranged  according  to  their  hardness.  The  scale 
is  as  follows : 

1.  Talc.  6.     Feldspar. 

2.  Gypsum.  7.     Quartz. 

3.  Calcite.  8.     Topaz. 

4.  Fluorite.  9.     Corundum. 

5.  Apatite.  10.     Diamond. 

To  assist  in  remembering  the  minerals  of  this  scale  in  their  order, 
the  following  mnemonic  has  been  devised: 

Tall  Gipsy  Girl  Flew  Up 

Talc.  Gypsum.  Calcite.  Fluorite.  Apatite. 

Fells  Queer  To  Go  Die 

Feldspar.         Quartz.  Topaz.          Corundum.          Diamond. 

The  position  of  a  mineral  in  this  scale  is  determined  by  the  minerals 
which  it  scratches.  Thus  if  a  mineral  scratches  feldspar,  but  is  scratched 
by  quartz,  its  hardness  would  be  stated  as  6.5.  In  order  to  test  hard- 
ness, pieces  of  the  minerals  of  the  scale  should  be  at  hand.  Fragments 
of  the  mineral  to  be  tested  may  be  grasped  in  the  fingers  and  rubbed 
upon  a  polished  surface  of  the  minerals  of  the  scale,  or  the  test  can 
often  be  more  accurately  made  by  rubbing  upon  the  mineral  of  the  scale  a 
coarse  powder  of  the  mineral  to  be  tested,  by  means  of  a  soft  pine  stick. 

17 


With  a  little  practice  one  may  become  so  good  a  judge  of  the  hard- 
ness of  a  mineral,  by  its  behavior  towards  an  ordinary  pocket-knife, 
that  the  minerals  of  the  scale  below  7  may  be  dispensed  with.  Thus 
minerals  of  the  first  two  degrees  of  hardness  may  be  scratched  with 
the  finger  nail ;  No.  3  can  be  deeply  scratched  with  a  knife ;  No.  4  less 
deeply  and  easily ;  No.  5  still  less  so ;  while  No.  6  is  about  the  hardness 
of  the  knife.  No.  6  also  scratches  ordinary  window  glass.  Upon  No.  7 
a  knife  blade  makes  no  impression,  the  steel  rubbing  off  on  the  mineral. 
Steel  of  the  hardness  of  a  file,  however,  scratches  quartz  slightly.  These 
tests  are  especially  useful  for  distinguishing  glass  imitations  from  gems 
of  the  hardness  of  quartz  and  higher.  Instead  of  a  file  it  is  well 
to  use  a  point  of  hardened  steel  to  avoid  danger  of  injuring  delicate 
gems.  Rubbing  the  gem,  especially  if  cut,  with  an  aluminum  pencil? 
is  a  still  better  means  of  testing  hardness  in  the  higher  numbers  of  the 
scale,  as  it  involves  no  danger  of  injury  to  the  stone.  Upon  soft 
stones  such  a  pencil  leaves  a  conspicuous  mark,  but  upon  hard  ones  none 
whatever.  Minerals  above  7  in  hardness  are  harder  than  a  file.  Corun- 
dum scratches  all  minerals  except  diamond,  and  diamond  is  the  hardest 
substance  known. 

Some  minerals,  if  crystallized,  are  somewhat  harder  in  one  direction 
than  another,  the  mineral  cyanite  being  a  notable  illustration  of  this. 
Ordinarily,  however,  the  hardness  of  a  mineral  is  about  the  same  in 
all  directions. 

Table  showing  hardness  of  gem  minerals : 

Diamond  -                                     -  10  Epidote  6.5 
Corundum  (Ruby,  Sapphire,  etc.)  9  Prehnite  -  -     6.5 
Chrysoberyl  8.5  Pyrite  -                                              6.5 
Topaz  8  Feldspar  (Amazonstone,  Moon- 
Spinel  (Balas  Kuby)      -  8-7.75          stone,  Labradorite,  etc.)         -     6 
Phenacite                                       -  7.75  Turquois      -                                     6 
Beryl    (Emerald,    Aquamarine,  Diopside  -  -     6 

etc.)  -  7.75  Nephrite  5.75 

Zircon  (Hyacinth)     -  7.5  Opal  -     5.5-6.5 

Euclase  7.5  Moldavite     -  5.5 

Staurolite  -  7.5  Obsidian  -  -     5.5 

Andalusite    -  7.25  Hematite      -  5.5 

lolite  -  7.25  Sphene     -  -     5.5 

Tourmaline  -  7.25  Lapis  Lazuli  5.5 

Garnet       -  -  7  Hauynite  -     5.5 

Quartz  (Amethyst,  Rock  Crystal,  Cyanite  5-7 

Jasper,  etc.)       -  7  Dioptase  -  -     5 

Jadeite      -  -  6.75  Fluorite        -  4 

Axinite  6.75  Malachite  -     3.5 

Chalcedony    (Agate,    Carnelian,  Jet       -  3.5 

etc.)  -  6.5  Amber      -  -     2.5 

Chrysolite     -  6.5  Gypsum  (Alabaster,  Satinspar, 

Vesuvianite       -  -  6.5  etc.)  2 

18 


SPECIFIC    GRAVITY 

The  specific  gravity  of  mineral  species  is  also  one  of  their  funda- 
mental and  constant  characters,  and  furnishes  a  reliable  means  of  dis- 
tinguishing between  gems  of  different  kinds,  and  of  separating  false 
from  real  stones.  To  be  sure,  a  variation  of  composition  may  cause 
a  variation  of  specific  gravity  in  the  same  species;  but  this  is  usually 
within  comparatively  narrow  limits.  The  different  kinds  of  garnet, 
or  of  tourmaline,  for  example,  possess  specific  gravities  varying  within 
one  integer;  but  the  varieties  are  usually  distinguished  by  colors  by 
which  the  appropriate  specific  gravity  can  be  judged.  One  great  advan- 
tage of  using  specific  gravity  as  a  means  of  identifying  gems  is,  that  the 
determination  can  be  made  without  danger  of  injuring  the  stone,  which 
is  more  than  can  be  said  of  tests  of  hardness,  fusibility,  or  behavior 
with  acids.  While  specific  gravity  can  usually  be  used  for  distinguish- 
ing between  gems,  as,  for  example,  between  quartz  as  compared  with 
diamond,  it  cannot  always  be  used  for  identifying  glass,  since  by  the 
addition  of  different  ingredients  it  is  possible  to  make  glass  of  vary- 
ing specific  gravity,  and  similar  to  that  of  the  gem  which  it  is  sought 
to  imitate. 

The  specific  gravity  of  a  substance  is  its  weight  as  compared  with 
that  of  an  equal  volume  of  water.  When  it  is  stated  that  the  specific 
gravity  of  topaz,  for  example,  is  3.55,  the  figures  simply  mean  that 
a  given  volume  of  topaz  is  3.55  times  heavier  than  the  same  volume 
of  water. 

Various  means  may  be  taken  to  determine  the  specific  gravity  of  a  body, 
the  most  obvious  and  simple  depending  upon  the  fact  that  a  body  heavier 
than  water  loses,  when  weighed  in  that  liquid,  a  weight  equal  to  that 
of  an  equal  volume  of  water.  Hence  by  weighing  a  body  first  in 
air  and  then  in  water,  and  dividing  the  weight  in  air  by  the  differ- 
ence between  the  weight  in  air  and  the  weight  in  water,  or  in  other 
words,  by  the  loss  of  weight  in  water,  the  quotient  will  be  the  specific 
gravity. 

The  following  example  of  a  determination  of  the  specific  gravity 
of  a  sapphire  will  illustrate  this: 

19 


The  weight  in  grams  in  air  was  -       12.89 

The  weight  in  grams  in  water  was  9.68 

Difference       -  3.21 

12.89  -r-  3.21  =  4.015,  the  specific  gravity. 

A  similar  quotient  will  be  obtained  whether  large  or  small  pieces 
are  taken  for  determination,  the  specific  gravity  being  totally  inde- 
pendent of  the  actual  gravity  or  weight. 

The  determination  of  the  specific  gravity  of  gems  or  minerals  becomes 
then  a  question  simply  of  manipulations  by  which  the  relative  weights 
of  the  substance  in  water  and  air  can  be  obtained  in  the  easiest  and 
most  accurate  way. 

The  most  common  and  generally  the  most  convenient  way  of  doing 
this  is  by  obtaining  the  weights  of  the  stone  in  water  and  air  directly 
by  means  of  a  delicate  balance.  The  stone  is  first  weighed  in  air 
and  the  weight  recorded.  It  is  then  put  into  a  holder  of  fine  plati- 
num wire,  bent  into  a  spiral  form,  and  suspended  from  the  arm  of  the 
balance.  The  length  of  the  wire  is  such  as  to  allow  the  stone  to  become 
completely  immersed  in  a  vessel  of  water  supported  on  a  stand  above  the 
scale  pan,  but  in  such  a  manner  as  to  allow  the  pan  to  swing  free.  In 
this  way  the  weight  of  the  stone  and  wire  in  water  can  be  accurately 
taken.  The  stone  is  then  removed,  and  the  wire  weighed  suspended 
in  the  water  as  before.  The  weight  of  this  is  subtracted  from  the 
previous  weight,  so  as  to  remove  the  weight  of  the  wire  from  the 
calculation,  and  the  remainder  is  the  loss  of  weight  of  the  stone  in 
water.  Dividing  the  weight  of  the  stone  in  air  by  this  remainder 
gives,  as  stated  above,  the  specific  gravity.  Several  precautions  need 
to  be  taken  to  insure  accurate  results.  In  the  first  place,  only  dis- 
tilled water  should  be  used,  as  ordinary  waters  have  higher  density. 
Again,  bubbles  of  air  often  adhere  to  the  surface  of  the  stone,  especially 
if  it  be  rough,  or  if  it  is  pervaded  by  cracks,  which  would  obviously, 
if  allowed  to  remain,  lessen  the  weight.  These  can  sometimes  Be 
removed  by  dipping  the  stone  in  water  several  times  and  blowing 
the  water  off,  or  they  can  surely  be  destroyed  by  boiling  for  a  few 
minutes  the  water  in  which  the  stone  is  immersed,  and  then  allow- 
ing it  to  cool  before  the  specific  gravity  is  taken. 

Strictly  speaking,  the  specific  gravity  of  a  body  is  its  weight 
compared  with  that  of  water  at  the  temperature  of  4°  Centigrade 
(39.2°  Fahrenheit),  which  is  the  point  at  which  the  density  of  water 
is  the  greatest.  Determinations  at  other  temperatures  should,  therefore, 
if  absolute  accuracy  is  desired,  be  corrected  to  4°  C.  In  practice,  however, 
the  error  is  so  trifling  that  it  may  be  disregarded  in  all  ordinary  deter- 

20 


minations,  especially  if  the  temperature  of  the  water  is  no  higher  than 
that  of  the  ordinary  living-room,  say  60°  F.  (15.6°  C.) 

In  case  an  accurate  balance  cannot  be  obtained,  a  beam  balance 
described  by  Professor  Penfield,  and  shown  in  the  accompanying  cut, 
can  be  constructed  by  almost  any  one.  This  gives  sufficiently  accurate 
results  for  all  practical  purposes.  It  consists  of  a  beam  of  wood  sup- 
ported on  a  fine  wire,  or  needle,  at  o.  This  must  swing  freely.  The 
long  arm,  oc,  is  divided  into  inches  and  tenths,  or  into  any  decimal 
scale,  commencing  at  the  fulcrum,  o;  the  short  arm  carries  a  double 
arrangement  of  pans,  so  suspended  that  one  of  them  is  in  the  air  and 
the  other  in  water.  A  piece  of  lead  on  the  short  arm  serves  to  almost 
balance  the  long  arm ;  and,  the  pans  being  empty,  the  beam  is  brought 


Specific  Gravity  Balance 

to  a  horizontal  position,  marked  on  the  upright,  near  c,  by  means  of 
a  rider,  d.  A  number  of  counterpoises  of  different  weights  are  needed. 
These  may  be  pieces  of  bent  wire,  or  bits  of  glass  tube,  with  a  wire 
hook  fused  into  one  end,  g,  some  of  them  containing  one,  two,  three, 
or  more  shot,  so  as  to  give  a  variety  of  weights.  The  beam  being 
adjusted  by  means  of  the  rider,  c?,  the  stone  or  mineral  which  it 
is  desired  to  test  is  placed  in  the  upper  pan,  and  a  counterpoise  is 
chosen,  which,  when  placed  near  the  end  of  the  long  arm,  will  bring 
it  into  a  horizontal  position.  The  weight,  TFa,  of  the  mineral  in  air, 
is  given  by  the  position  of  the  counterpoise  on  the  scale.  The  min- 
eral is  next  transferred  to  the  lower  pan,  and  the  same  counterpoise 
is  brought  nearer  the  fulcrum,  o,  until  the  beam  becomes  again  hori- 
zontal, when  its  position  gives  the  weight,  Ww,  of  the  mineral  in  water. 
Then  Wa  divided  by  Wa — Ww,  gives  the  specific  gravity. 

A  quick,  convenient,  and  accurate  means  of  separating  minerals,  and 
especially  cut  stones,  according  to  their  specific  gravity,  is  afforded  by  use 
of  the  so-called  heavy  liquids.  The  employment  of  these  depends  upon 
the  fact  that  a  substance  will  float  upon  the  top  of  a  liquid  of  greater 
density  than  itself,  will  remain  suspended  in  a  liquid  of  exactly  the 
same  density  as  itself,  and  will  sink  to  the  bottom  of  a  liquid  of  lower 

21 


density  than  itself.  Now,  a  number  of  liquids  are  known  which  are 
considerably  heavier  than  water,  but  whose  specific  gravity  may  be  low- 
ered very  gradually  by  the  addition  of  water  or  other  liquid  to  them. 
If  a  stone  placed  in  one  of  these  liquids  remains  floating  it  is  lighter 
than  the  liquid.  By  reducing  the  density  of  the  liquid  a  point  may 
be  reached  where  the  specific  gravity  of  the  two  is  equal,  and  the 
stone  will  remain  suspended  somewhere  within  the  liquid.  Ascertain- 
ing the  specific  gravity  of  the  liquid  gives,  therefore,  that  of  the  stone. 
Or  of  two  stones  supposed  to  be  identical,  if  one  sinks  in  the  liquid 
as  it  is  gradually  diluted,  long  before  the  other,  a  considerable  differ- 
ence of  specific  gravity  is  indicated,  and  the  stones  are  doubtless 
of  different  species.  Here,  as  in  making  determinations  of  specific 
gravity  by  weight,  the  relative  size  of  the  stones  does  not  need  ordi- 
narily to  be  taken  into  consideration. 

The  heavy  liquids  principally  employed  for  the  above  purposes  are 
the  following:  A.  solution  of  potassium  mercuric  iodide,  known 
as  Thoulet's  or  Sonstadt's  solution,  having  a  specific  gravity  of  3.15; 
methylen  iodide,  whose  maximum  specific  gravity  is  3.32;  and  silver 
thallium  nitrate,  which  on  fusing  yields  a  liquid  with  a  maximum 
specific  gravity  of  4.5-5.  The  first,  or  Thoulet's  solution,  is  prepared 
by  treating  five  parts  by  weight  of  mercuric  iodide  and  four  parts 
by  weight  of  potassium  iodide  in  a  porcelain  dish  with  a  little  water 
and  evaporating  until  a  crust  begins  to  form.  The  solution  can  then 
be  reduced  to  a  desired  density  by  adding  distilled  water,  or  can 
be  brought  back  to  the  maximum  specific  gravity  by  evaporating  the 
water.  It  can  be  kept  indefinitely  if  placed  in  closely  stopped  bottles, 
especially  if  a  few  drops  of  mercury  be  added.  It  is  poisonous.  In 
using  it,  steel  pincers  or  glass  rods  should  be  employed  for  immersing 
the  stones,  as  the  insertion  of  brass  instruments  causes  a  decomposition 
of  the  liquid,  and  a  deposition  of  mercury  upon  the  metal. 

While  the  Thoulet  solution  is  the  cheapest  and  easiest  of  the  heavy 
liquids  to  manipulate,  its  rather  low  density  prevents  its  use  for  gems 
having  a  specific  gravity  much  over  3,  and  hence  some  of  the  other 
liquids  are  often  preferred.  Methylen  iodide  is  recommended  by  Bauer 
as  best  suited  for  the  general  purposes  of  the  student  of  gems.  This 
has,  as  stated,  a  maximum  density  of  3.32;  but  by  saturating  with 
iodine  and  iodoform  a  density  of  3.6  may  be  obtained.  The  useful- 
ness of  the  latter  mixture  is  somewhat  impaired,  however,  by  its  very 
dark  color. 

The  dilution  of  methylen  iodide  is  performed  by  means  of  benzol 
rather  than  by  water.  Bauer  recommends  having  for  use  four  differ- 

22 


ent  strengths  of  the  liquid,  which  may  be  preserved  in  four  labeled 
bottles  side  by  side.  By  dropping  the  stone  whose  specific  gravity 
it  is  desired  to  test,  into  different  bottles  successively,  its  specific  gravity 
can  be  learned  within  narrow  limits.  It  is  recommended  to  place  in  the 
first  bottle  a  solution  of  methylen  iodide  saturated  with  iodine  and 
iodoform.  Its  specific  gravity  would  be  3.6.  The  second  bottle 
should  contain  pure  methylen  iodide,  marking  a  specific  gravity 
of  3.3.  The  third  bottle  may  contain  the  same,  diluted  until  its  specific 
gravity  becomes  3.0,  and  the  fourth  the  liquid  reduced  to  a  specific 
gravity  of  2.65,  which  is  that  of  quartz.  Topaz  and  diamond  would 
then  float  upon  the  first  liquid,  but  sink  in  the  second.  Hyacinth, 
ruby,  and  sapphire,  would  sink  in  all.  Beryl,  emerald,  etc.,  would 
float  upon  the  first  three,  but  sink  in  the  last,  and  so  on. 

The  bottles  containing  the  solutions  should  be  kept  tightly  stoppered, 
as  any  evaporation  affects  the  density  of  the  liquid.  Methylen  iodide 
is  a  somewhat  expensive  chemical,  costing,  as  it  does,  $1.25  an  ounce; 
but  when  a  supply  is  once  obtained  it  will  last  almost  indefinitely. 

Instead  of  having  solutions  of  different  densities  at  hand,  some  pre- 
fer to  have  ready  for  use  fragments  of  minerals  of  different  densities 
arranged  in  series.  These  are  called  indicators,  and  are  used  by  placing 
one  or  more  in  the  liquid  with  the  stone  whose  specific  gravity  is  desired, 
and  diluting  until  the  indicator  sinks  or  rises  at  the  same  time  with 
the  unknown  mineral.  The  unknown  mineral  must  then  be  of  the 
same  specific  gravity  as  the  indicator. 

For  minerals  with  a  specific  gravity  above  3.6,  the  only  heavy  liquid 
available  is  silver  thallium  nitrate.  This,  as  previously  stated,  fuses 
to  a  clear  liquid  having  a  density  of  4.5  to  5.  The  temperature  required 
for  fusion  is  about  75°  Centigrade  (167°  F.),  and  the  work  can  be  con- 
veniently done  by  heating  the  salt  in  a  beaker  upon  a  water  bath. 
The  dilution  can  be  performed  by  adding  hot  water.  The  necessity 
of  working  always  with  hot  liquids  is  of  course  a  drawback  to  the 
use  of  this  substance,  and  it  is  also  a  costly  chemical.  In  other 
respects  it  answers  well  the  purposes  of  a  heavy  liquid.  It  should 
be  noted  in  the  use  of  all  the  heavy  liquids  that  the  addition  of  a  very 
small  amount  of  water,  or  other  diluting  liquid,  is  sufficient  to  consid- 
erably reduce  the  specific  gravity.  Hence,  the  addition  of  the  diluting 
liquid  should  be  made  very  slowly  and  carefully,  with  frequent  stirring, 
and  a  constant  watch  on  the  position  of  the  stone  that  is  being  tested. 
For  the  purpose  of  determining  exactly  the  specific  gravity  of  the 
liquid  at  any  point,  some  form  of  balance  is  usually  employed,  that 
known  as  Westphal's  giving  quick  and  accurate  results.  It  is,  however, 

23 


a  somewhat  expensive  piece  of  apparatus,  and  any  one  not  wishing 
to  incur  such  an  outlay  may  obtain  results  nearly  as  good  with  the 
beam  balance  previously  described.  In  its  use  for  this  purpose  a  sinker 
in  the  shape  of  a  cylindrical  bulb  is  suspended  from  a  position  marked 
by  a  notch  near  the  end  of  the  long  arm.  By  putting  shot  in  the 
pans  and  using  the  rider  d,  the  beam  is  brought  to  a  horizontal 
position  with  the  sinker  in  air.  The  sinker  is  then  immersed  in 
the  heavy  solution,  and  a  weight  is  selected,  which,  when  placed 
near  the  end  of  the  beam  will  bring  the  latter  to  a  horizontal  position. 
The  position  of  this  weight  gives  relatively  the  weight  of  the  heavy 
solution  displaced  by  the  sinker.  After  washing,  the  sinker  is  immersed 
in  water,  and  the  same  weight  is  placed  nearer  the  fulcrum  until  the 
beam  becomes  horizontal.  The  position  of  this  weight  gives  relatively 
the  weight  of  the  water  displaced  by  the  sinker.  The  larger  weight 
divided  by  the  smaller  gives  the  desired  specific  gravity. 

By  employing  proper  formulae,  weights  of  bodies  may  be  found  if 
their  specific  gravities  be  known,  or  the  specific  gravity  of  one,  if  its 
weight  and  the  weight  and  specific  gravity  of  another  be  known. 

Thus  if  a  diamond  is  set  in  a  gold  ring,  it  is  often  desirable  to  know 
the  weight  of  the  diamond,  or  its  specific  gravity,  or  the  specific  gravity, 
and  hence  the  fineness,  of  the  gold  of  which  the  ring  is  composed,  with- 
out removing  the  stone.  Each  of  these  values,  and  even  others,  can  be 
found  by  employing  the  following  formulae.  These  are  derived  from 
two  equations  in  which  A  represents  the  weight  of  the  stone,  a  its  specific* 
gravity;  B  the  weight  of  the  gold,  and  b  its  specific  gravity;  and  C  the 
combined  weight  of  the  ring  and  stone,  and  c  their  specific  gravity. 

Then  A  +  B  =  C 

A^B     C 

and  _+__= — 

a       b      c 
Whence  we  obtain  for  A, 

A  =  C  (b  —  c)a 
(b  —  a)  c 

for  a,  Abe 


C(b  — c)  +  Ac 

for  b,  i  _          B  a  c 

=  C(a  — c)  +  Bc 

and  expressions  for  other  factors  if  desired. 


TABLE   SHOWING   SPECIFIC   GRAVITY   OF   GEM   MINERALS 


Zircon  (Hyacinth) 

Almandine  Garnet    - 

Ruby  - 

Sapphire 

Cape  Ruby  (Garnet)     - 

Demantoid  (Garnet) 

Staurolite    - 

Pyrope  (Garnet) 

Chrysoberyl 

Cyanite   - 

Cinnamon  Stone  (Garnet) 

Spinel  (Balas  Ruby) 

Topaz 

Diamond 

Epidote 

Vesuvianite 

Sphene 

Chrysolite 

Jadeite 

Axinite    - 

Diopside 

Dioptase 

Andalusite 

Apatite    - 

Hiddenite    - 


4.60-4.70 

Green  and  Blue  Tourmaline   -     3.11-3.16 

4.11-4.23 

Euclase    - 

3.05 

4.08 

Fluorspar 

-,   3.02-3.19 

4.06 

Nephrite 

3.00 

3.86 

Phenacite 

-     2.98-3.00 

3.83 

Red  and  Colorless  Tourmaline     2.94-3.08 

3.73-3.74 

Turquois 

2.60-2.80 

3.69-3.78 

Labradorite 

-     2.70 

3.68-3.78 

Beryl 

2.68-2.75 

3.60-3.70 

Emerald 

-     2.67 

3.60-3.65 

Rock  Crystal   ^ 

3.60-3.63 

Smoky  Quartz 

3.50-3.56 

Amethyst 

.      -                   2.65-2.66 

3.50-3.52 

Jasper 

3.35-3.50 

Chrysoprase 

3.35-3.45 

lolite 

-     2.60-2.65 

3.35-3.45 

Chalcedony       j 

2.60 

3.33-3.37 

Agate                 i 

3.30 

Obsidian  - 

-     2.50-2.60 

3.29-3.30 

Moonstone  (Adular)                    2.55 

3.20-3.30 

Lapis  lazuli 

-     2.40 

3.29 

Moldavite 

2.36 

3.17-3.19 

Opal    - 

-     2.19-2.20 

3.16-3.22 

Jet 

1.35 

3.15-3.20 

Amber 

-     1.00-1.11 

25 


OPTICAL  QUALITIES 

Since  the  pleasing  qualities  of  gems  depend  largely  upon  their  effects 
upon  light,  some  general  statements  as  to  the  properties  of  light,  and  the 
manner  in  which  it  is  affected  in  passing  through  gems,  will  be  desirable. 
The  generally  accepted  theory  of  the  transmission  of  light  is  that  it 
moves  in  a  straight  line  without  change  of  direction  in  one  and  the  same 
homogeneous  medium,  as  vibrations  of  particles  of  the  luminiferous 
ether  which  may  be  called  light  waves,  and  which  take  place  at  right 
angles  to  the  direction  of  transmission.  In  some  media  the  velocity 
of  transmission  of  light  is  independent  of  the  direction  in  which  it  is 
propagated.  Such  media  are  called  isotropic,  and  include  among  gems, 
opal,  diamond,  spinel,  and  garnet.  In  other  media  the  velocity  of  trans- 
mission of  light  varies  in  different  directions.  Such  media  are  said  to 
be  anisotropic.  Most  gems  belong  to  this  class  of  bodies.  The  velocity 
of  transmission  of  light  through  different  media  differs,  but  has  an 
absolute  value  for  one  and  the  same  substance. 

Media  in  which  light  is  transmitted  at  a  high  velocity  are  said  to 
be  optically  rare,  those  in  which  it  is  transmitted  at  a  low  velocity  are 
said  to  be  optically  dense.  In  passing  from  one  medium  to  another  of 
different  density,  as  for  instance  from  air  into  water,  light  undergoes  a 
change  in  its  rate  of  transmission  and  a  change  of  direction.  This  change 
constitutes  the  phenomenon  of  refraction,  the  most  familiar  illustration 
of  which  is  seen  in  the  apparent  bending  of  a  stick 
partly  immersed  in  water.  If  the  amount  of  this 
change  of  direction  be  studied,  it  will  be  found  to 
have  a  definite  angular  value  which  is  constant  for  the 
same  substance.  Thus,  if  in  the  accompanying  figure 
a  ray  of  light  passing  through  the  air  from  L  be  sup- 
posed to  fall  upon  the  surface  of  water  at  A,  it  will  be 
refracted  in  the  direction  A  K.  The  angle  L  A  B  is 
Diagram  illustrating  caue(j  the  angle  of  incidence,  and  K  A  C  the  angle  of 

refraction  of  lignt 

refraction,  B  C  being  a  perpendicular  to  the  water's 
surface.  If  from  A  as  a  center  a  circle  B  C  be  described,  and  from  the 
points  ra  and  p  where  this  circle  cuts  the  incident  and  refracted  rays 
the  lines  ra  n  and  p  q  be  drawn  perpendicular  to  B  C,  then  will 

26 


m  n  be  the  sine  of  the  angle  of  incidence,  and  p  q  the  sine  of  the  angle 
of  refraction.  Now,  it  is  found  that  whatever  the  direction  of  the 
incident  ray,  that  of  the  corresponding  refracted  ray  is  so  conditioned 
that  the  quotient  of  the  sine  of  the  angle  of  refraction  into  the  sine 
of  the  angle  of  incidence  is  a  constant  quantity  for  the  same  media. 
This  quotient  is  called  the  index  of  refraction.  It  is  to  be  found  in  the 
instance  above  quoted  by  dividing  m  n  by  p  q.  The  greater  the  refractive 
power  of  the  substance  the  smaller  will  be  the  value  of  p  q,  and  the  larger 
the  quotient,  which  is  the  index  of  refraction.  Hence  substances  with 
a  high  refractive  power  have  a  large  index  of  refraction,  as  diamond, 
whose  index  of  refraction  is  2.42.  That  of  water  is  only  1.336.  Garnet 
has  an  index  of  refraction  varying  from  1.75  to  1.81  in  different  varie- 
ties. Zircon  is  another  gem  mineral  which  possesses  a  high  index  of 
of  refraction,  this  being  1.96.  Diamond  is  the  most  highly  refractive 
of  the  gems,  however. 

It  is  to  be  noted  that  the  amount  of  refraction  of  the  different  com- 
ponent colors  of  a  ray  of  white  light  is  a  variable  quantity,  and  hence  in 
every  refraction  the  ray  is  broken  up  in  a  way  similar  to  that  in  which 
it  is  separated  into  the  colors  of  the  spectrum  in  passing  through  a 
prism.  This  variation  in  the  refraction  of  the  different  colors  is  called 
dispersion.  The  red  waves,  for  example,  suffer  less  change  of  velocity 
than  the  blue,  and  hence  the  refractive  index  for  a  given  substance  is 
greater  for  blue  than  for  red  light.  Substances  differ  in  the  degree  of 
refraction  which  the  waves  of  the  different  colors  suffer  in  passing  through 
them,  and  hence  in  the  degree  to  which  they  separate  the  component 
colors ;  that  is,  they  differ  in  what  is  called  dispersive  power.  Diamond 
has  high  dispersive  power,  its  index  of  refraction  for  red  light  being 
2.407+,  and  for  violet  light  2.464+,  while  spinel,  which  has  only  an 
average  dispersive  power,  has  a  difference  in  indices  between  red  and 
violet  light  only  between  1.712-f-  for  red,  and  1.726  for  violet. 

A  particular  phase  of  the  relations  of  the  incident  and  refracted  rays 
should  be  noted  here,  as  it  has  much  to  do  with  increasing  the  brilliancy 
of  gems. 

When  a  ray  of  light  attempts  to  pass  from  a  denser  into  a  rarer 
medium  there  are  conditions  under  which  the  angle  of  refraction  cannot 
be  greater  than  the  angle  of  incidence.  Under  such  circumstances  the 
ray  cannot  emerge  from  the  denser  medium,  but  will  be  wholly  reflected 
at  the  point  of  incidence.  Thus,  in  the  following  figure,  if  the  lumin- 
ous rays  from  A  passing  out  of  the  water  be  traced  it  will  be  found  that 
since  the  angle  of  refraction  increases  more  rapidly  than  that  of  incidence 
certain  rays  cannot  emerge  at  all,  but  are  refracted  or  reflected  back  into 

27 


Diagram  showing  paths  of 
rays  passing  from  a  dense  into 
a  rare  medium 


the  water.  This  is  familiarly  illustrated  in  looking  into  a  glass  of  water 
held  above  the  eye,  by  the  fact  that  the  surface  of  the  water  appears 
to  be  silvered  and  opaque,  owing  to  the  total  reflection  of  a  large  num- 
ber of  rays.  The  path  of  the  rays  is  more 
fully  illustrated  in  the  next  figure,  showing  a 
ray  of  light,  L  A,  passing  out  of  the  water  by 
refraction  in  the  direction  A  R.  If  the  angle 
of  incidence,  C  A  L,  be  gradually  increased, 
the  angle  of  refraction  will  also  increase,  but 
more  rapidly  than  the  angle  of  incidence  until 
it  becomes  equal  to  90°,  when  the  ray  will 
graze  the  surface  of  the  water  at  A  M.  If 
the  source  of  light  be  still  further  removed  as 
to  Z,  the  ray  can  no  longer  pass  out,  but  is  reflected  to  r.  The  inci- 
dent angle  at  which  internal  reflection  will  thus  take  the  place  of  refrac- 
tion is  called  for  every  substance  the  critical  or  limiting  angle,  and  is 
a  constant  angle  for  each  different  substance.  For  water  (with  refer- 
ence to  air)  this  angle  is  48°35',  for  flint  glass  37°36',  and  for  diamond 
23°  53 ' .  Substances  with  a  low  critical  angle — or  in  other  words,  highly 
refracting  substances — will  appear  more  brilliant  than  those  of  low 
refractive  power,  because  the  amount  of  light  striking  upon  them  becomes 
concentrated  into  a  smaller  part  of  the  surface. 
This  can  be  proved  by  a  mathematical  calculation, 
but  it  is  too  abstruse  for  these  pages.  The  fact, 
however,  can  be  made  evident  by  observation.  A 
large  amount  of  total  reflection,  such  as  is  afforded 
by  substances  of  high  refractive  power,  has, 
moreover,  the  advantage  of  returning  light  to 
the  eye  which  would  otherwise  pass  through  the 
stone  and  be  lost.  How  this  is  done  is  shown  by 
the  following  figure  after  Bauer,  representing 
the  path  of  a  ray  of  light  in  a  diamond  cut 
as  a  brilliant.  The  ray  enters  in  the  direction  a  b  and  being  totally 
reflected  from  the  various  points  of  the  interior  comes  back  in  some- 
what the  general  direction  m  g  in  which  it  started.  It  does  not  come 
back,  however,  as  a  single  ray,  but  is  broken  up  by  the  refraction  into 
its  differently  colored  components.  Hence  the  particular  ray  which 
reaches  the  eye  may  be  red  or  blue,  or  some  other  color.  To  this 
refractive  power,  therefore,  the  diamond  owes  the  property  of  flashing 
colored  lights  which  gives  it  so  much  of  its  beauty  and  attractiveness. 
When  refraction,  or  reflection,  of  a  ray  of  light  takes  place,  the  ray 

28 


Diagram  illustrating  re- 
fraction of  light  at  different 
angles 


undergoes  another  change,  known  as  polarization.  Polarized  light  is 
that  having  vibrations  taking  place  in  a  single  plane  instead  of  in  an 
innumerable  number  of  planes,  as  is  the  case  with  ordinary  light.  A 
partial  polarization  of  light  occurs  with  every 
refraction  and  reflection,  but  it  is  not  complete.  By 
means  of  proper  appliances  a  perfect  polarization  can 
be  obtained.  Polarized  light  is  of  great  advantage  in 
the  optical  study  of  gems,  since  it  affords  a  ray  the 
plane  of  whose  vibrations  can  be  accurately  ascer- 
tained. Light  may  be  polarized  by  causing  it  to  be 

reflected  from  two  mirrors,  and  an  instrument  some- 
Path  of  a  ray  of  light 

times  used  for  obtaining  polarized  light  is  constructed     in  a  diamond  cut  as  a 

.1  .          .      .   i  '       rrn  i  17  brilliant.    After  Bauer 

upon  this  principle.     Ine  most  commonly  used  polar- 
izer, however,  is  the  so-called  Nicol  prism,  an  appliance  constructed  from 
two  pieces  of  Iceland  spar,  in  a  manner  which  can  best  be  understood 
when  the  subject  of  double  refraction  has  first  been  considered. 

Light  propagated  in  the  anisotropic  media  previously  mentioned, 
instead  of  advancing  in  all  directions  with  the  same  velocity,  as  is  the 
case  with  isotropic  media,  advances  in  different  directions  with  different 
velocities.  These  directions  resolve  themselves  into  two,  corresponding 
to  the  directions  of  the  greatest  and  least  elasticity  in  the  medium. 
A  ray  of  light  entering  such  a  medium  is  therefore  broken  up 
into  two  rays,  which  have  distinct  properties  and  move  independently 
of  each  other.  The  refraction  of  the  ray  instead  of  being  single, 
as  is  the  case  with  isotropic  media,  is  double,  and  such  media  are 
hence  said  to  be  doubly  refracting.  To  this  class  belong  most  gems, 
since  substances  crystallizing  in  any  of  the  systems  except  the  isometric, 
unless  they  are  amorphous,  possess  this  property.  The  most  familiar 
illustration  of  the  double  refraction  of  light  is  seen  when  an  object  such 
as  a  black  cross  upon  paper  or  a  line  of  ordinary  print  is  looked  at 
through  a  piece  of  Iceland  spar.  The  characters  when  thus  seen  appear 
double,  and  of  only  about  half  their  normal  intensity,  except  where  two 
images  may  come  together.  The  phenomenon  is  more  evident  in  Iceland 
spar  than  in  other  minerals  because  the  two  rays  are  more  widely  separ- 
ated in  this  substance  than  is  usually  the  case,  but  the  breaking  up  into 
two  rays  and  the  separation  take  place  in  many  other  minerals  neverthe- 
less. The  two  rays  are  known  for  distinction  as  the  ordinary  and  extraor- 
dinary rays.  Each  is  polarized,  so  that  it  is  evident  that  if  some  means 
can  be  found  of  eliminating  one  of  them,  the  other  may  be  made  to 
furnish  a  convenient  source  of  polarized  light.  This  is  what  is  done  in 
the  construction  of  the  Nicol  prism,  it  being  made  of  two  pieces  of 

29 


IE 

Construc- 
tion of  the 
Nicol  prism 


Iceland  spar  cut  in  definite  directions,  and  cemented  together  by  Canada 
balsam.  The  construction  is  shown  in  the  accompanying  figure.  The 
parallelogram  represents  the  outline  of  the  prism,  and  the  line  running 
nearly  as  a  diagonal  shows  where  the  two  parts  are  joined 
together. 

A  ray  of  light,  m  n,  falling  upon  the  prism  is  at  once 
refracted  into  two  rays,  n  0  and  n  E.  The  ray  n  0  upon 
reaching  the  layer  of  balsam  is  totally  reflected,  and  passes 
out  at  Oj,  where  it  disappears.  The  ray  n  E,  however, 
passes  through,  and  reaches  the  eye  as  a  ray  of  polarized 
light,  having  its  vibrations  in  a  single  plane.  If  now  this 
ray  fall  upon  another  Nicol  prism  standing  in  the  same 
vertical  direction,  and  similarly  oriented,  it  can  pass 
through  without  sensible  loss  or  change,  and  so  on  through 
a  large  number  if  necessary.  If,  however,  the  second  prism 
while  maintaining  the  same  vertical  direction  be  rotated  90° 
about  its  vertical  axis,  the  ray  upon  reaching  it  will  follow 
the  path  n  0  instead  of  n  E,  since  the  ordinary  and  extraordinary  rays 
are  situated  at  right  angles  to  each  other.  It  will  therefore  be  absorbed 
and  lost,  and  no  light  will  reach  the  eye. 

If  a  plate  of  a  singly  refracting  substance  be  interposed  between  the 
two  prisms,  no  change  will  occur  in  the  above-named  phenomena ;  but  if 
a  doubly  refracting  mineral  be  inserted  instead,  the  field  of  view  will 
light  up,  except  in  four  positions,  90°  from  each  other.  It  is  obvious 
that  the  passage  of  light  through  the  second  prism  in  the  latter  case 
comes  from  the  fact  that  the  polarized  light  from  the  first  prism  is 
broken  up  into  two  rays  in  traversing  the  doubly  refracting  plate,  one  of 
which  is  traveling  in  such  a  direction  as  will  permit  it  to  pass  through 
the  second  prism.  These  differences  of  behavior  of  doubly  refracting 
as  compared  with  singly  refracting  bodies  afford  a  convenient  and  ac- 
curate means  of  distinguishing  gems,  for  the  tests  can  be  made  with- 
out danger  of  injury  to  the  stones.  The  essential  features  of  an 
apparatus  for  the  purpose  are  two  Nicol  prisms  set  in  a  frame  one 
above  the  other,  with  a  stage,  preferably  a  revolving  one,  between. 
One  of  the  prisms  must  be  capable  of  being  rotated  about  its  axis. 
The  lower  prism  is  usually  called  the  polarizer;  the  upper  one  the 
analyzer.  Having  turned  the  prisms  with  reference  to  each  other  so 
that  the  field  of  view  is  dark,  when  a  singly  refracting  substance,  such 
as  diamond,  spinel,  garnet,  or  glass,  is  inserted  between  the  two,  no  light- 
ing up  of  the  field  can  be  observed  except  such  as  may  come  from  a 
reflection  from  facets  of  the  object.  This  reflection  should  not  be  con- 

30 


founded  with  an  appearance  of  transmitted  light.  A  doubly  refracting 
stone  will,  however,  when  inserted,  be  lighted  internally,  showing  much 
the  same  color,  though  less  strongly,  as  that  which  it  possesses  in  ordinary 
light.  On  revolving  the  stone  by  means  of  the  movable  stage,  it  will 
be  seen  to  become  dark  four  times  during  a  complete  revolution,  the 
intervals  of  darkness  occurring  every  90°  from  each  other. 

Thus  quartz  may  be  distinguished  from  diamond,  quartz  from  glass, 
zircon  from  diamond,  or  any  doubly  refracting  stone  from  a  glass  imita- 
tion, and  so  on.  Diamond  cannot  be  distinguished  from  glass,  nor  from 
spinel,  by  this  test,  since  all  are  singly  refracting.  Other  tests,  such  as 
those  of  specific  gravity  and  hardness,  will,  however,  be  sufficient  to 
distinguish  in  such  cases.  It  is  of  course  true  that  stones  cut  from 
doubly  refracting  minerals  in  certain  directions  appear  like  singly 
refracting  ones,  and  a  possible  error  may  be  made  on  this  account.  In 
practice,  however,  the  likelihood  of  meeting  with  stones  cut  in  just  such 
directions  is  very  small,  and  may  be  ignored.  An  apparatus  constructed 
for  the  determination  of  gems  by  the  above  methods  is  illustrated  in  the 
following  figure  (p.  32).*  Here  the  polarization  of  the  light  below  the 
stone  is  accomplished  by  means  of  two  mirrors,  and  thus  the  cost  of 
one  Nicol  prism  is  saved.  The  stone  is  placed  upon  the  stage  d.  The 
light,  polarized  by  the  mirrors,  passes  through  the  stone  into  the  tube 
above  containing  the  analyzer,  and  through  this  to  the  eye.  By  rotat- 
ing the  tube  in  the  holder  /,  the  distinction  in  appearance  between 
singly  and  doubly  refracting  minerals  can  be  readily  seen.  The  ordi- 
nary petrographical  microscope  also  affords  the  necessary  appliances 
for  determinations  of  this  kind.  Tourmaline  tongs  furnish  another  com- 
bination of  a  polarizer  and  analyzer,  but  they  allow  too  little  light  to 
pass  through  to  be  of  practical  value  for  determining  minerals. 

Doubly  refracting  substances  have  another  feature  in  distinction  from 
singly  refracting  ones,  in  the  fact  that  the  rays  passing  through  them  are 
differently  absorbed,  and  hence  give  different  colors  in  several  directions, 
while  singly  refracting  substances  are  normally  of  the  same  color  in  all  di- 
rections. In  the  degree  to  which  they  exhibit  this  property  of  dichroism, 
or  pleochroism,  as  it  is  called,  minerals  vary.  lolite  is  one  of  the  most 
strongly  dichroic  minerals,  and  can  plainly  be  seen  to  be  dark  blue  in  one 
direction  and  clove-brown  in  another.  Transparent  zircon  is  often  pinkish 
brown  in  color  when  looked  at  it  in  the  direction  of  the  vertical  axis,  and 
asparagus-green  when  seen  laterally.  Tourmaline  is  often  nearly  opaque 
when  looked  at  in  the  direction  of  the  vertical  axis,  but  transparent  when 

*  This  instrument  can  be  obtained  of  R.  Fuess,  Steglitz  bei  Berlin,  Germany,  at  a  cost  of 
eighteen  to  twenty  dollars. 

31 


seen  laterally.  In  other  doubly  refracting  minerals  the  dichroism  may 
not  be  sufficiently  apparent  to  be  positively  observed  with  the  naked  eye. 
The  detection  of  the  dichroic  character  can  usually  be  made,  however, 
with  the  aid  of  the  little  instrument  known  as  the  dichroscope.*  This 
consists  of  an  oblong  rhombohedron  of  Iceland  spar  with  a  glass  prism 


Instrument  for  examining  gems  in  polarized  light 

of  18°  cemented  to  each  extremity,  or  with  the  end  faces  ground  and 
polished  so  as  to  be  perpendicular  to  the  length  of  the  prism.  It  is 
placed  in  a  metallic  cylindrical  case,  and  is  provided  with  a  convex  lens 
at  one  end,  and  a  square  hole  at  the  other,  the  focal  length  of  the  lens 
being  such  as  to  show  a  distinct  image  of  the  square  opening.  On  look- 

*  This  instrument  can  be  obtained  of  Negretti  &  Zambra,  38  Holborn  Viaduct,  London, 
at  a  cost  of  about  five  dollars. 


ing  through  the  dichroscope  the  square  hole  appears  double,  since  both 
the  ordinary  and  extraordinary  ray  give  an  image.  If  a  piece  of  mineral 
or  cut  stone  is  held  in  front  of  it,  two  images  of  this  are  likewise  seen. 
These  images  are  of  different  colors  if  the  mineral  is  a  doubly  refracting 
one,  since  the  two  rays  are  differently  absorbed  in  passing  through  such 
a  mineral.  The  two  images  being  side  by  side  even  slight  differences 
of  color  can  be  perceived.  The  following  are  some  of  the  twin  colors 
exhibited  by  the  more  important  gems  when  viewed  in  this  manner,  as 
stated  by  Church : 

NAME  OF  STONE  , — TWIN  COLORS — s 

Sapphire  (blue),  Greenish  straw,  Blue. 

Euby  (red),  Aurora-red,  Carmine-red. 

Tourmaline  (red),  Salmon,  Rose-pink. 

"          (brownish  red),  Umber-brown,  Columbine-red. 

"          (brown),  Orange-brown,  Greenish  yellow. 

"          (green),  Pistachio-green,  Bluish  green. 

"          (blue),  Greenish  gray,  Indigo-blue. 

Topaz  (sherry),  Straw-yellow,  Eose-pink. 

Peridot  (pistachio),  Brown-yellow,  Sea-green. 

Aquamarine  (sea-green),  Straw-white,  Gray-blue. 

Beryl  (pale  blue),  Sea-green,  Azure. 

Chrysoberyl  (yellow),  Golden  brown,  Greenish  yellow, 

lolite,  Pale  buff,  Indigo-blue. 

Amethyst,  Keddish  purple,  Bluish  purple. 

The  dichroscope  thus  affords  a  convenient  and  accurate  means  of 
distinguishing  gems.  Any  one  of  those  in  the  above  list,  for  example, 
could  be  distinguished  from  a  glass  imitation  by  the  fact  that  any  glass 
substitute  would  give  two  images  of  exactly  the  same  color,  instead  of 
different  colors,  as  would  the  genuine  stone.  Such  gems  as  diamond, 
garnet,  and  spinel  cannot,  however,  be  distinguished  from  glass  or  each 
other  in  this  manner,  since  they  give  similarly  colored  images. 


33 


ELECTRICAL  PROPERTIES,  PHOSPHOR- 
ESCENCE, AND  FLUORESCENCE 

All  gems  when  rubbed  upon  cloth  become,  like  glass,  positively 
electrified.  Gems  differ,  however,  in  the  length  of  time  during  which 
they  will  retain  an  electrical  charge.  Thus  tourmaline  and  topaz  remain 
electric  under  favorable  conditions  for  several  hours ;  but  diamond  loses 
its  electricity  within  half  an  hour.  The  electrical  peculiarities  of  differ- 
ent species  were  at  one  time  used  quite  extensively  for  identifying 
them;  but  owing  to  different  behavior  under  different  atmospheric 
conditions  little  use  is  now  made  of  such  tests.  Besides  developing 
electricity  by  friction  some  gems  become  electric  upon  heating.  Such 
are  said  to  be  pyro-electric.  To  test  a  stone,  or  rough  piece  of  mineral 
for  this  property,  it  can  conveniently  be  held  in  forceps  and  heated 
gently  in  a  colorless  flame,  such  as  that  of  a  Bunsen  burner  or  alcohol 
lamp.  The  amount  of  heating  should  not  be  much  over  100°  C.  On 
withdrawing  the  stone,  it  will,  as  it  cools,  if  pyro-electric,  attract  bits 
of  tissue  paper  or  straws.  Tourmaline  is  perhaps  the  most  strongly 
pyro-electric  of  the  minerals  used  as  gems,  and  the  property  affords 
a  means  for  identifying  it.  Topaz  is  another  gem  mineral  which 
usually  exhibits  this  property.  Some  topaz  also  becomes  electric  when 
subjected  to  simple  pressure.  This  is  said  to  be  true  of  some  crystals 
of  Brazilian  topaz  if  they  are  pressed  between  the  ringers  in  the  direc- 
tion of  the  vertical  axis.  Electricity  developed  in  this  way  is  known 
as  piezo-electricity. 

Simple  tests  for  all  these  kinds  of  electricity  consist  in  the  attrac- 
tion of  light  objects,  such  as  bits  of  tissue  paper,  cat  hairs,  pith  balls 
suspended  by  silk  threads,  etc.  They  are  best  made  when  the  atmos- 
phere is  dry,  the  winter  season  being  especially  favorable. 

Some  gems  have  the  property  of  emitting  light  after  heating,  exposure 
to  light,  or  an  electrical  discharge.  This  property  is  known  as  phosphor- 
escence, since  the  glow,  although  it  is  often  of  different  colors,  resembles 
that  emitted  by  phosphorus.  The  diamond  is  a  mineral  which  exhibits 
this  property,  some  of  its  gems  after  exposure  to  sunlight  for  a  short 
time  emitting  a  glow  which  can  be  plainly  seen  in  a  dark  room.  This 
is  often  stated  to  be  a  property  of  all  diamond,  but  this  is  incorrect, 

34 


some  stones  exhibiting  no  change  whatever  after  exposure  to  sunlight. 
Phosphorescence  may  also  be  called  out  in  the  diamond  by  rubbing  it, 
especially  across  the  fibers  of  a  piece  of  wood.  Among  all  minerals 
phosphorescence  is  best  exhibited  by  fluorite,  nearly  all  specimens 
of  which  will,  when  gently  heated,  emit  a  visible  light.  The  color 
of  the  light  varies  with  different  varieties,  and  is  usually  not  the  same 
as  the  natural  color  of  the  mineral.  The  tints  exhibited  are  usually 
greenish,  bluish,  or  purplish.  On  increased  heating  the  phosphorescence 
disappears,  and  cannot  be  restored  again  except  by  passing  an  electric 
discharge  through  the  mineral,  whereupon  the  lost  power  is  usually 
regained.  The  same  is  true  of  diamond.  It  is  generally  supposed 
that  the  phosphorescence  of  minerals  results  from  the  presence  within 
them  of  particles  of  organic  matter  of  the  nature  of  hydrocarbons, 
which  are  aroused  to  a  certain  activity  on  heating.  Of  the  exact 
nature  of  the  phenomenon,  however,  little  further  is  known. 

Closely  allied  to  phosphorescence  is  fluorescence,  which,  in  a  strict 
sense,  is  the  emission  of  light  within  a  substance  while  it  is  being 
exposed   to   light,  or  in  some   cases   to   an   electrical  discharge  from 
a  vacuum   tube.     Fluorite   is   again  the  mineral  which  best   exhibits 
this  property,  a  beam  of  white  light  passing  through  a  colorless  cube 
of  it  producing  a  delicate  violet  color.    The  diamond,  ruby,  and  other 
gems   are   stated   by  Dana   to   give   forth 
a  brilliant  fluorescence  when  exposed  to  an 
electrical  discharge  from  the  negative  pole 
of  a  vacuum  tube.   Fluorescence  is  also  pro- 
duced in  the  diamond  by  radio-active  sub- 
stances; that  is,  by  radium,  or  substances 
possessing  its  activity.     In  this  respect  dia- 
mond differs  from  such  gem  minerals  as 
ruby,  emerald,  topaz,  etc.,  and  from  glass, 
in  none  of  which  do  the  radium  rays  excite 

much  activity.  X-ray  photograph  of  paste  and 

The  behavior  of  gems  toward  X-rays  or     ^idn  taring  a?  «£*&,  to 


n   rays  Varies  with  different  species,      opaque;  the  real  diamonds,  in  the 
,      ™      ,  j.   ,  .    .  .         .  ,  .  ring  at  the  right,  transparent. 

and  artords  a  means  ot  distinguishing  them. 

Thus  diamond  is  quite  transparent  to  the  rays,  while  glass  is  opaque. 
Accordingly,  in  an  X-ray  photograph,  such  as  is  shown  in  the  accom- 
panying figure,  of  two  rings,  the  one  set  with  diamonds,  the  other  with 
paste,  the  diamond  can  readily  be  known  by  its  transparency. 

The  behavior  of  others  of  the  gem  minerals  in  relation  to  the  X-rays 
is  further  shown  in  the  following  table  : 

35 


COMPLETELY  TRANSPARENT. 

Amber. 

Jet. 

Diamond. 

STRONGLY    TRANSPARENT. 

Corundum. 

TRANSPARENT. 

Opal. 

Andalusite. 
Cyanite. 
Chrysoberyl. 

SEMI-TRANSPARENT. 

Quartz. 
Labradorite. 
Adular. 
Topaz. 


SLIGHTLY   TRANSPARENT. 

Spinel. 

Essonite  (Garnet). 

Fluorite. 

ALMOST  OPAQUE. 

Gypsum. 
Turquois. 
Tourmaline. 
Calcite. 

OPAQUE. 

Almandite  (Garnet). 

Beryl. 

Epidote. 

Rutile. 

Hematite. 

Pyrite. 

Zircon. 


36 


CRYSTAL   FORM 

The  crystal  form  of  minerals  serves  as  an  important  means  of  identi- 
fying them,  since  crystals  of  each  species,  in  any  system,  except  the 
isometric,  have  forms  peculiar  to  that  species.  The  actual  determi- 
nation of  species  in  this  way,  however,  requires  a  careful  measurement 
of  angles,  trigonometrical  calculations,  and  a  knowledge  of  crystal  forms 
obtained  through  a  study  of  that  branch  of  mineralogy  known  as  crystal- 
lography. The  mastery  of  this  subject  is  usually  beyond  the  purpose 
of  the  student  of  gems,  nor  is  it  essential.  A  more  practical  need 


Distortion  of  a  cubical  crystal  by  variations  in  growth 

for  him  is  to  obtain  a  certain  empirical  familiarity  with  the  common 
external  forms  of  the  crystals  of  each  species,  together  with  a  knowl- 
edge of  the  ways  in  which  distortion  may  occur,  preventing  recognition 
of  the  regular  forms. 

In  the  following  pages,  under  most  of  the  species,  are  given  illus- 
trations of  the  common  forms  of  those  species,  which  one  soon  learns 
to  associate  with  that  particular  mineral. 

In  all  comparisons  of  figures  with  actual  crystals,  however,  it  must 
be  remembered  that  crystals  in  nature  rarely  present  the  complete, 
symmetrical  form  which  the  geometrical  figure  would  indicate.  While 
the  angles  between  the  faces  remain  practically  always  the  same,  there 
occur  much  distortion  and  imperfect  growth  of  crystals  which  may 
be  quite  misleading.  Certain  faces  may  be  so  much  developed  that 
others  which  would  normally  be  present,  do  not  appear  at  all;  and 
again,  the  attachment  of  the  crystal  to  its  matrix  often  prevents  develop- 
ment of  the  complete  form,  or  obscures  its  presence. 

Thus  in  the  above  figure  the  cube,  which  would  be  the  normal  crystal 
form,  may  become  by  continued  growth  in  the  vertical  direction  elon- 

37 


gated  like  the  form  shown  at  its  right,  or  by  growth  laterally  the  tabular 
form  shown  may  be  produced. 

So  again,  the  quartz  crystals  represented  below  are  all  made  up  of 
the  same  faces  and  have  the  same  interfacial  angles,  yet  they  would  seem 


+c 


-fa 


.— o 


Forms  of  quartz  crystals  produced  by  distortion 

at  first  sight  to  have  no  similarity  of  form.  One  can  soon  become  famil- 
iar with  these  variations,  however,  and  by  making  due  allowance  for 
them  learn  to  recognize  crystal  forms  quickly  and  accurately. 

In  addition  to  an  empirical  familiarity  with  the  forms  of  crystals, 
some  knowledge  of  the  general  groups  of  crys- 
tals  is  desirable,  since  there  are  thus  expressed 
relations  which  characterize  not  only  the  ex- 
ternal form,  but  internal  structure. 

The  forms  into  which  a  mineral,  or  any 
substance  of  definite  chemical  composition, 
may  crystallize,  are  divided  into  six  systems. 
These  are  known  as  the  isometric,  tetragonal, 
hexagonal,  orthorhombic,  monoclinic,  and  tri- 
clinic  systems.  By  some  a  seventh,  called  the 
rhombohedral  system,  is  added,  though  here  it 
is  considered  a  subdivision  of  the  hexagonal. 
In  the  discrimination  of  crystal  forms,  the 
relations  of  the  planes  can  best  be  expressed 
by  referring  them  to  a  series  of  three  or  more 
imaginary  axes  within  the  crystal.  One  of 
these,  known  as  a,  is  supposed  to  run  from 
front  to  back  ;  another,  known  as  6,  from  Crystal  Axes 

right  to  left  ;  and  the  third,  known  as  c,  vertically  The  latter  is  known 
as  the  vertical  axis,  and  the  two  former  are  designated  as  lateral  axes. 
In  the  hexagonal  system,  the  existence  of  three  lateral  axes  is  assumed. 

The  differences  between  the  six  systems  can  be  stated  in  terms  of 
these  axes  as  follows: 


In  the  isometric  system  the  axes  are  of  equal  length,  and  at  right 
angles  to  each  other.  In  the  tetragonal  system  one  axis,  usually  taken 
as  the  vertical,  is  longer  or  shorter  than  the  other  two,  which  are  equal 
in  length.  The  axes  are  all  at  right  angles  to  each  other,  however.  In 
the  hexagonal  system  one  axis,  usually  taken  as  the  vertical,  is  longer 
or  shorter  than  the  lateral  axes  and  at  right  angles  to  them.  The 
lateral  axes  are  three  in  number,  of  equal  length,  and  meet  at  angles 
of  60°.  In  the  orthorhombic  system  the  three  axes  are  of  unequal 
length,  but  meet  at  right  angles.  In  the  monoclinic  system  the  three 
axes  are  of  unequal  length.  Two  of  them  meet  at  right  angles,  while 
the  third  is  inclined.  In  the  triclinic  system  the  axes 
are  of  unequal  length,  and  meet  at  unequal  angles. 

The  axial  relations  above  class- 
ified are  paralleled  in  the  symmetry, 
both     external 
and   internal,   of 


Cube 
Crystals.       Thus  Octahedron 

crystals   of    the 

isometric  system  are  the  most  highly  Dodec^edron 
symmetrical,  and  those  of  the  tri- 
clinic system  the  least  so.  By  symmetry  is  here  Trapezohedron 
understood  the  relation  which  an  object  has  to  its 
reflection  in  a  mirror ;  and  another  way  of  stating  the  previous  obser- 
vation would  be  to  say  that  an  isometric  crystal  can  be  held  before 
a  mirror  in  more  positions  in  which  the  crystal  and  its  reflection 
present  the  same  appearance,  than  one  of  any  other  system,  while  with 
a  triclinic  crystal  no  such  position  can  be  found.  Besides  the  division 
into  six  systems,  each  system  is  itself  subdivided  into  groups  of  varying 
kinds  of  symmetry.  There  are  thirty-two  of  these  groups,  characterized 
by  a  particular  kind  of  symmetry,  and  a  substance  crystallizing  in  a 
certain  group  will  invariably  show  that  symmetry. 

A  few  simple  forms  peculiar  to  different  systems  may  be  mentioned 
here,  since  the  terms  will  be  often  employed  in  the  text.  Four  common 
forms,  exhibited  by  minerals  crystallizing  in  the  isometric  system,  are 
the  cube,  octahedron,  dodecahedron,  and  trapezohedron.  The  cube  is 
a  solid  bounded  by  six  similar  faces,  each  parallel  to  two  of  the  axes. 
Each  face  is  a  square,  and  the  interfacial  angles  are  all  90°.  Crystals 
of  this  form  are  exhibited  by  pyrite,  fluorspar,  and  rarely  by  diamond. 
The  octahedron  is  bounded  by  eight  similar  faces,  meeting  the  axes 

39 


Tetragonal  prism  and 
pyramid 


at  equal  distances.  Each  face  is  an  equilateral  triangle.  Diamond  and 
spinel  are  gem  minerals  which  often  exhibit  crystals  of  this  form. 
The  dodecahedron  is  bounded  by  twelve  faces,  each  of  which  meets 
two  of  the  axes  at  equal  distances,  and  is  parallel  to  a  third  axis. 
Each  face  is  a  rhomb.  Garnet  quite  commonly  crystallizes  in  this  form, 
as  well  as  in  that  of  the  next  type,  the  trapezo- 
hedron.  The  trapezohedron  is  bounded  by 
twenty-four  faces,  each  of  which  is  a  trapezium. 
Each  face  intersects  one  axis  at  the  unit  length, 
and  meets  the  other  two  axes  at  distances 
greater  than  unity.  The  form  bears  some  rela- 
tion in  appearance  to  the  octahedron,  if  it  be 
imagined  that  three  faces  of  the  trapezohedron 
occupy  the  place  of  one  face  of  the  octahedron. 
In  other  systems  than  the  isometric,  the 
simplest  and  in  general  the  most  commonly  occurring  forms  are  prisms 
and  pyramids.  Prisms  are  forms  whose  faces  are  parallel  to  the  vertical 
axis,  while  they  meet  the  lateral  ones;  pyramids  are  forms  whose 
planes  meet  all  three  of  the  axes. 

In  the  hexagonal  system  prismatic  and  pyramidal  faces  occur  in 
multiples  of  three,  while  in  the  tetragonal,  orthorhombic,  etc.,  systems, 
they  occur  in  multiples  of  two.  Thus  a  crystal  of  zircon 
may  be  distinguished  from  one  of  quartz,  for  example,  by 
the  fact  that  on  the  former  four  or  eight  similar  pris- 
matic faces  may  be  counted,  on  the  latter,  three  or  six. 

Substances  vary  considerably  in  their  tendency  to  form 
distinct  crystals,  or  even  to  crystallize.  Quartz,  in  the 
form  of  rock  crystal  and  amethyst,  is  generally  found  in 
distinct  crystals,  while  agate,  chalcedony,  etc.,  although 
crystalline,  and  of  the  same  composition,  never  form 
separate  crystals.  .  Such  substances  as  opal,  turquois, 
obsidian,  and  obviously  those  of  organic  origin,  such  as  amber,  jet, 
pearl,  and  coral,  never  crystallize,  or  possess  regular  external  form. 
Such  substances  are  termed  amorphous.  As  a  rule,  gem  minerals  are 
those  tending  to  occur  in  distinct  crystals,  since  crystallization  usually 
favors  transparency  and  purity  of  substance. 


Hexagonal 
prism  and 
pyramid 


40 


CUTTING  AND  MOUNTING 

The  condition  in  which  gems  are  found  in  nature  is  rarely  such 
as,  according  to  the  general  notion  of  human  kind,  exhibits  their 
greatest  beauty.  In  the  state  of  nature,  the  surfaces  of  gems  are  gen- 
erally dull  and  lusterless ;  their  shape  is  irregular,  and  their  mass  is  per- 
meated by  flaws  and  imperfections.  Moreover,  the  powers  of  reflection 
and  refraction  of  light,  which  give  gems  their  superior  brilliancy  and 
fire,  can  only  be  brought  out  in  perfection  when  the  stones  are  shaped 
with  reference  to  their  internal  structure.  Hence,  from  the  earliest 
times,  man  has  endeavored  to  increase  the  beauty  of  gems  by  bring- 
ing them  to  a  condition  of  the  highest  possible  polish  and  luster. 

The  progress  of  this  art  has  been  a  gradual  and  slow  one;  but  in 
its  present  development  it  affords  an  opportunity  for.  the  exercise 
of  knowledge  and  skill  of  a  high  order.  It  is  true  that  from  time  to 
time  certain  art  critics,  among  whom  was  Ruskin,  have  urged  that  gems 
in  their  native  state  are  more  beautiful  than  when  cut,  but  such  views 
overlook  the  obvious  enhancing  of  the  optical  qualities  of  a  gem  by  a  proper 
cutting.  The  mere  facetting  of  a  stone  may  be,  as  these  critics  claim, 
an  expression  of  a  somewhat  vulgar  taste ;  but  cutting  a  stone  with 
reference  to  its  optical  structure  applies  an  intelligent  skill  which  can 
but  prove  enhancing  to  its  natural  beauty.  Occasionally  a  diamond 
or  ruby  crystal  is  found  of  sufficient  regularity  of  form  and  purity 
to  make  it  available  in  its  natural  state  for  use  as  a  gem ;  but  ordinarily 
the  art  of  the  lapidary  is  needed  to  bring  from  precious  stones  an  exhi- 
bition of  their  full  beauties,  and  fit  them  for  the  highest  purposes  of 
ornament.  On  the  other  hand,  there  is  a  common  notion  as  to  the 
amount  of  improvement  that  can  be  made  in  a  stone  by  cutting  or 
facetting,  which  is  generally  a  mistaken  one.  There  is  no  stone  so  dull 
and  lusterless  that  some  one  will  not  think  that  it  would  be  beautiful  if 
it  could  only  be  cut  and  polished.  But  as  a  matter  of  fact,  cutting  or 
polishing  usually  changes  the  appearance  of  a  stone  very  little,  and  a 
stone  which  is  not  attractive  in  color  and  transparency  before  cutting  is 
not  likely  to  be  after.  The  skilled  lapidary,  it  is  true,  can  select  the 
most  favorable  parts  of  a  mass  for  cutting,  but  more  than  this  he  cannot 
do;  and  much  disappointment  may  be  avoided  if  only  those  stones  are 

41 


cut  which  can  be  seen  while  in  the  rough  to  have  the  necessary  desir- 
able qualities. 

The  first  effort  on  the  part  of  man  to  improve  upon  the  natural 
appearance  of  gems  was  confined  to  giving  them  a  simple  polish. 
At  first  only  the  natural  surfaces  were  polished,  but  later  the  rough 
corners  were  rounded,  and  gradually  the  plan  of  giving  them  a  symmet- 
rical shape  developed.  To  this  day,  however,  the  treatment  of  gems 


A  Ceylonese  gem  cutter  of  the  present  day 

in  the  Orient  is  confined  largely  to  rounding  and  polishing  the  stones, 
with  little  alteration  of  their  natural  shape.  The  Kohinoor  diamond 
in  the  form  in  which  it  reached  England  is  an  illustration  of  the 
unsymmetrical  shape  which  is  allowed  by  Orientals  to  be  retained 
by  even  their  most  costly  gems.  The  appliances  by  which  this  work 
of  polishing  and  cutting  gems  is  still  performed  in  the  East  are  of  the 
crudest  kind,  and  show  little  advancement  from  the  earliest  types  used. 
The  accompanying  cut  shows  how  a  Ceylonese  gem-cutter  of  the  pres- 
ent day  plies  his  trade.  His  wheel  is  supported  on  two  upright  pegs 
set  in  the  floor  timbers  of  his  house.  A  wooden  axle,  on  the  end 

42 


of  which  is  the  disk  for  polishing,  is  inserted  in  these.  The  axle, 
and  thus  the  disk,  is  rotated  by  pushing  back  and  forth  upon  it  with 
the  right  hand  a  long  stick  to  which  is  fastened  a  string  passing  once 
around  the  axle.  The  stone  to  be  polished  is  held  against  this  revolv- 
ing disk  by  the  left  hand,  either  with  the  fingers  directly,  or  by  a  stick 
to  which  the  stone  has  been  cemented.  Abrasive  powders  and  water 
are  contained  in  bowls  made  by  sawing  cocoanut  shells  in  two,  and 
the  abrasive  is  applied  to  the  wheel  by  dipping  the  stone  at  intervals 
into  the  mixture.  By  this  painfully  slow  and  laborious  process  the 
polishing  of  the  gem  is  in  time  accomplished. 

Among  Occidental  peoples,  the  cutting  of  gems  was  early  carried 
to  a  much  higher  point  than  among  Orientals.  By  both  Greeks  and 
Romans  gems  were  given  a  symmetrical  form,  and  they  carried  to 
a  high  degree  of  perfection  the  art  of  cutting  cameos  and  intaglios 
from  them. 

The  different  forms  into  which  precious  stones  are  cut  at  the  pres- 
ent time  may  be  arranged  in  two  groups:  (1),  those  having  plane  sur- 
faces; and  (2),  those  having  curved  surfaces,  although  the  two  may 
be  combined  in  the  same  cutting.  The  different  forms  under  these 
subdivisions  may  be  grouped,  following  Church,  thus: 


1.     Plane  surface  cuttings  -    -    -    - 


Brilliant. 

Step  or  Trap. 

Mixed  or  Brilliant  Top. 


Table. 
Rose. 
(  Single  cabochon. 

Double  cabochon. 
2.     Curved  surface  cuttings     -    -     -     -     -s   TT  „ 

Hollow  cabochon. 

I  Tallow  top. 

Of  these  cuttings,  those  of  the  first  group  are  usually  used  for 
transparent  stones,  such  as  the  diamond,  emerald,  and  ruby;  and  those 
of  the  second  for  translucent  and  opaque  gems,  such  as  the  opal, 
turquois,  moonstone,  cat's -eye,  and  the  like.  The  garnet  is  cut  in 
both  ways,  the  cabochon-cut  garnet  being  called  a  carbuncle. 

The  question  as  to  which  form  of  cutting  should  be  used  for  any 
particular  gem  is  one  involving  considerations  of  the  mineral  species 
and  the  peculiarities  of  each  individual  stone.  On  the  one  hand,  it 
is  desirable  to  avoid  as  little  loss  of  the  stone  as  possible;  and  on  the 
other,  to  give  it  that  shape  and  proportion  which  shall  best  bring  out 
its  luster,  brilliancy,  and  color.  Pale  stones  should,  for  instance, 
have  greater  depth  than  dark  ones;  the  latter  should  be  given  more 

43 


"  spread"  and  less  depth.  A  well -cut  stone  is  worth  considerably 
more  than  a  poorly  cut  one,  even  if  the  latter  has  a  greater  weight. 
Often  in  cutting  a  stone  one-half  and  even  more  of  its  mass  may 
be  removed,  and  yet  the  stone  be  improved  thereby.  The  brilliancy 
of  a  stone  is  increased,  other  things  being  equal,  the  larger  the  num- 
ber of  facets  which  can  be  given  it.  The  value  of  the  stone  must  be 
taken  into  consideration  in  this  connection,  however.  Stones  of  mod- 
erate value  do  not  have  their  worth  sufficiently  increased  by  addition 
of  numerous  facets  to  warrant  the  expenditure  of  the  extra  time  and 
labor  that  would  be  required  to  bring  them  to  this  condition.  If  a  stone 
is  strongly  dichroic,  as  is  iolite  for  example,  the  cutting  must  be  in 


Side  view  of  brilliant 


Brilliant  seen  from 
above.  SK,  skill  facets  ; 
QU,  quoins  or  lozenges  ; 
ST,  star  facets;  CR, 
cross  or  skew  facets; 
TEMP,  templets  or  bezils 


Brilliant  seen  from  be- 
low. SK,  skill  facets ; 
CR,  cross  facets 


such  a  direction  as  to  bring  out  this  quality  in  the  highest  degree. 
Similarly  tourmaline,  because  of  its  dichroic  properties,  may  make 
a  dark  and  uninteresting  stone  if  cut  at  right  angles  to  the  crystal- 
lographic  axis,  while  if  cut  parallel  to  this  axis  it  will  make  a  bril- 
liant appearance  and  show  two  colors.  Such  stones  as  moonstone, 
labradorite,  tiger's-eye,  and  others,  which  show  chatoyancy  only  in 
certain  directions,  must  obviously  be  cut  with  reference  to  this  fea- 
ture. In  transparent  stones,  the  angle  which  the  upper  and  lower 
facets  make  with  each  other  should  be  a  definite  one,  so  as  to  reflect 
the  light  in  the  best  possible  manner. 

Considering  briefly  and  in  order  the  forms  of  cutting  above  men- 
tioned, we  may  note  first  the  brilliant.  The  brilliant  cut  is  said  to  have 
been  invented  by  Cardinal  Mazarin  in  his  endeavors  to  introduce  the  art 
of  diamond-cutting  into  France.  It  is  now  the  form  most  commonly  given 
diamonds  and  is  employed  for  many  other  transparent  stones  as  well. 
As  will  be  seen  from  the  above  figure,  it  is  made  up  essentially  of 
two  truncated  pyramids  joined  by  their  bases,  the  upper  pyramid 
leaving  one -third  and  the  lower  pyramid  two -thirds  of  the  length 
of  the  stone.  The  upper  pyramid  is  called  the  crown,  the  lower  the 

44 


pavilion.  The  plane  on  which  they  join,  and  which  represents  the 
greatest  breadth  of  the  stone,  is  the  girdle.  The  flat  top  of  the  upper 
pyramid  is  known  as  the  table.  It  should  be  four-ninths  of  the  breadth 
of  the  stone. .  The  corresponding  termination  of  the  lower  pyramid  is 
known  as  the  culet,  and  this  should  have  an  area  one-sixth  to  one-fifth 
of  that  of  the  table.  The  number  of  facets  given  these  pyramids 
varies  with  different  cuttings;  but  the  typical  has  fifty-eight,  which 
have  individual  names,  as  indicated  in  the  diagram. 

The  outline  of  the  brilliant  cut  is  not  always  so  nearly  circular 
as  in  the  form  shown  in  the  diagram,  although  this  is  usual.  Brilliants 

are  sometimes  cut  so  as  to  have  a  nearly  square 
outline,  or  again  they  may  be  made  triangular, 
or  again  oval. 

The  proportions  of  the  brilliant  above  given 
are  not  always  followed  by  lapidaries,  if  it  is 
deemed  that  they  would  involve  the  loss  of  too 
much  material,  or  if  the  cutter  believes  it  possible 
to  improve  the  effect  of  the  stone  by  depart- 
ing from  them.  The  former  consideration  has 
weighed  most  largely  in  the  cutting  of  some  cele- 
brated diamonds,  with  the  result  that  according 
to  some  critics  the  stones  do  not  show  to  the  best 

Trap  or  step  cut  as  seen       T  rrn         J.T       IT-   i  •  T  i    •      •- 

from  above  and  below  advantage.     Ihus  the  Kohmoor  diamond  in  its 

present  form  is  said  to  be  too  broad  for  its  depth, 
and  the  Regent  too  thick  for  its  breadth. 

The  second  cutting  to  be  noted  is  the  trap  or  step  cut.  This  is  a 
favorite  form  of  cutting  for  colored  stones.  It  is  a  shallower  cutting 
than  the  brilliant,  and  has  a  broader  table.  The  outline  is  commonly 
oblong,  in  contrast  to  the  more  nearly  circular  form  of  the  brilliant,  al- 
though quadrilateral,  hexagonal,  and  other  outlines  may  be  given.  The 
rules  of  proportion  are  far  less  strict  than  those  applied  to  the  brilliant. 
The  following  form  is  a  common  one,  however :  Beginning  with  the  table 
above,  two  sloping  or  step  facets  lead  to  the  girdle,  below  which  three  to 
five  or  more  sets,  or  zones  of  diminishing  steps,  extend  to  the  culet.  The 
latter  has  the  general  shape  of  the  stone.  The  number  of  the  facets  is  often 
increased  over  the  above  with  advantage.  A  common  fault  with  the 
step  cut  comes  from  making  the  table  too  broad,  since  the  internal 
reflections  from  the  lower  facets  are  best  seen,  as  Church  states,  through 
the  sloping  bezils  of  the  crown,  not  through  the  flat  surface  of  the  table. 
The  mixed  or  brilliant  top  cut  is  a  combination  of  the  brilliant  and 
step  cut. 

45 


Top  and  side  views  of 
table  cut 


The  table  cut  is  a  simpler  cutting  than  either  the  step  or  brilliant. 
It  consists  simply  of  a  table  with  beveled  edges.  It  is  an  old  form 
of  cutting,  and  is  generally  superseded  at  the  present  day  by  forms 
with  a  greater  number  of  facets. 

The  rose  cut  has  the  crown  facetted  all  over, 
the  table  of  the  brilliant  being  replaced  by  six 
triangular  facets,  and  the  other  facets  by  eighteen 
triangular  ones.  The  base  is  either  made  flat,  or 
as  a  duplicate  of  the  upper  part,  the  latter  cut 
giving  what  is  known  as  the  "  double  brilliant." 

The  rose  cut  is  especially  useful  for  small  or 
flat  diamonds,  as  by  means  of  it  well-cut  gems 
can  be  made  from  pieces  of  "  rough "  which  are 
too  small  or  too  thin  to  make  brilliants. 

Besides  the  brilliant  and  rose,  which  are  stan- 
dard cuttings  for  the  diamond,  there  are  several  quaint  and  fanciful 
cuts  which  are  now  more  or  less  in  vogue.  One  of  these  is  the 
"  pendeloque,"  a  sort  of  double  rose  cut,  and  the  "  briolette,"  also  a 
double  rose  cut  of  a  general  pear 
shape.  The  outline  of  the  stone 
may  be  varied  also,  so  as  to  be  tri- 
angular, hexagonal,  or  circular.  A 
form  of  diamond  cutting  which  is 
now  being  extensively  advertised  is 
that  called  the  "  twentieth  century  " 
cutting.  This  is  a  double  rose  cut 
with  eighty  planes,  forty  above  and  forty  below.  It 
is  made  up  essentially  of  two  cones  placed  base  to 
base,  both  completely  facetted  with  planes,  eight  of 
which  meet  around  each  apex.  The  supposed  supe- 
riority over  the  brilliant  rests  in  the  substitution  of 
facets  for  the  table  and  culet  of  the  latter. 

The  curved  cuttings  given  to  precious  stones  are 
all  modifications  of  the  form  known  as  cabochon,  the 
various  shapes  given  being  such  as  are  best  adapted 
to  bring  out  the  beauties  of  the  individual  stone 
which  is  to  be  cut.  The  different  forms  of  the 
cabochon  can  be  sufficiently  well  understood  by  refer- 
ence to  the  accompanying  figures.  The  hollow  cabo- 
chon serves  the  purpose  of  lightening  the  color  of 
dark  stones,  and  affording  a  place  for  inserting  a  foil. 

46 


Single  cabochon 


Rose  cut 


Double  cabochon 


Hollow  cabochon 


Flat  or  tallow-top 
cabochon 


Mixed  cabochon 


The  manner  in  which  the  actual  work  of  cutting  and  polishing 
gems  is  performed  by  the  most  advanced  methods  of  the  present  day 
varies  somewhat  with  the  kind  of  stone.  Some  stones  naturally  require 
a  much  harder  abrasive  than  others,  while  different  wheels  and  differ- 
ent polishing  powders  are  suited  to  different  gems.  In  general,  the 
stone  is  reduced  as  nearly  as  possible  to  the  desired  shape  by  careful 
cleaving  in  the  rough.  If  there  is  a  natural  cleavage  much  use  can 
be  made  of  this  in  bringing  the  stone  to  the  desired  shape ;  if  not, 
the  work  cannot  be  carried  far  in  this  manner.  Large  stones,  if  not 
too  hard,  can  be  sawed  to  a  desirable  shape  with  diamond  or  carbor- 
undum saws.  After  having  been  shaped  as  nearly  as  possible  by  one 
of  these  methods,  the  rough  stone  is  then  soldered  to  a  metal  handle, 
or  cemented  to  a  stick  by  means  of  wax  or  other  adhesive  substance, 
and  ground  to  a  rounded  symmetrical  shape  on  a  flat,  revolving  wheel, 
the  abrasive  used  being  applied  by  means  of  water  or  oil.  The  wheels 
used  are  generally  either  of  iron  or  copper,  though  lead,  tin,  and  even 
wooden  wheels  are  employed.  For  all  gems  except  the  diamond,  the 
cutting  of  which  can  be  carried  on  only  by  means  of  diamond  dust, 
emery  or  ground  corundum  is  the  abrasive  generally  used,,  although 
since  the  invention  of  carborundum  this  is  employed  quite  extensively. 
After  the  stone  has  received  a  general  rounding  in  this  manner,  the 
cutting  of  facets,  one  at  a  time,  is  begun.  To  maintain  the  exact 
I  angle  at  which  each  facet  is  to  be  cut,  a  clamp  is  provided  above  the 
wheel,  in  which  is  fastened  the  handle  on  which  the  gem  is  soldered. 
By  this  means  the  stone  is  held  against  the  wheel  at  the  desired 
angle  until  the  facet  is  cut.  For  facetting  cheap  stones  the  handle 
of  the  gem  is  sometimes  held  in  the  hand;  but  while  the  work 
can  be  done  faster  by  this  means  it  obviously  cannot  be  performed 
so  accurately.  After  the  stone  has  received  by  grinding  the  proper 
number  of  facets,  each  of  the  size  desired,  the  work  of  polishing  must 
be  performed.  This  is  done  in  a  similar  way  to  the  grinding,  except 
that  softer  abrasives  and  softer  wheels  are  used.  Rouge,  tripoli,  and 
"  putty  powder "  are  the  abrasives  most  commonly  used  for  this  pur- 
pose, they  being  applied  dry  or  moist  to  wheels  of  leather,  felt,  or  paper, 
against  which  the  stone  to  be  polished  is  held. 

Owing  to  its  superlative  hardness  the  cutting  of  the  diamond  must 
be  performed  by  a  somewhat  different  process  than  that  of  other  stones. 
The  facets  upon  a  diamond  are  cut  by  rubbing  together  by  hand  two 
diamonds  cemented  upon  sticks.  After  the  facets  have  been  outlined 
in  this  way  they  are  ground  and  polished  upon  wheels  to  which  diamond 
dust  is  applied,  in  a  manner  similar  to  that  described  for  other  gems. 

47 


The  grinding  and  polishing  of  agates  and  other  large  stones  are 
performed  at  Oberstein,  Germany,  on  an  extensive  scale,  in  mills 
fitted  up  in  the  manner  indicated  in  the  accompanying  cut.  The 
wheels  for  grinding  turn  vertically  instead  of  horizontally  as  is  usually 
the  arrangement  when  cutting  small  stones.  They  are  made  of  sand- 
stone, are  about  five  feet  in  diameter,  and  often  a  foot  in  thickness. 
Their  edges  are  often  fluted  in  different  shapes,  so  as  to  give  different 


Agate  cutting  at  Oberstein,  Germany.     After  Bauer 

desired  forms.  The  piece  to  be  cut  is  held  by  the  workman  by  hand 
against  the  wheel  until  it  has  received  the  desired  shape.  After  being 
ground  it  is  polished  on  a  wheel  of  hardwood  with  tripoli,  this  part  of 
the  work  being  usually  performed  by  women  and  children. 

After  a  gem  has  been  cut,  the  question  of  its  proper  mounting  and 
setting  must  next  be  considered.  While  some  gems  are  worn  unmounted, 
as  for  instance  the  pearls  of  a  necklace,  the  great  majority  are  set  in 
metal.  This  work  is  the  especial  art  of  the  goldsmith  or  jeweler,  and 
the  laity  usually  take  little  pains  to  be  informed  in  regard  to  it. 
There  is  room,  however,  for  the  development  of  a  much  higher  taste 
in  these  matters  than  exists  at  present.  The  average  buyer  is  con- 

48 


tent  to  know  that  the  article  which  he  purchases  contains  a  sapphire, 
emerald,  or  diamond,  representing  so  much  intrinsic  value,  without 
considering  whether  the  best  use  of  it,  from  an  artistic  point  of  view, 
has  been  made;  or  whether  for  the  same  outlay  much  more  pleasing 
effects  might  not  have  been  obtained  from  other  stones.  In  the  group- 
ing of  gems,  with  regard  to  effects  of  color,  luster,  texture,  etc.,  certain 
combinations  often  seen  are  far  from  ideal,  while  others  rarely  seen 
would  be  admirable.  Thus  a  combination  of  the  diamond  and  turquois 
is  not  a  proper  one,  since  the  opacity  of  the  latter  stone  deadens  the  lus- 
ter of  the  former.  The  cat's-eye  and  diamond  make  a  better  combination, 
and  so  do  the  more  familiar  diamond  and  pearl.  Colorless  stones,  such 
as  the  diamond  or  topaz,  associate  well  with  deep-colored  ones,  such  as 
amethyst  and  tourmaline,  each  serving  to  give  light  and  tone  to  the 
other.  Diamond  and  opal  as  a  rule  detract  from  each  other  when  in 
combination,  since  each  depends  upon  "  fire  "  for  its  attractiveness. 

Methods  of  mounting  gems  may  be  described  as  being  essentially 
two  in  number,  one  the  mount  a  jour,  and  the  other  the  encased 
mount.  The  mount  a  jour,  so  called  from  two  French  words  mean- 
ing to  the  light,  is  illustrated  in  the  well -known  manner  of  setting 
ring  stones,  by  which  the  stone  is  held  in  place  by  a  circlet  of  claws, 
exposing  it  to  view  on  all  sides.  This  mounting  is  especially  suited 
to  colorless  and  transparent  stones  without  flaws,  as  it  allows  the 
freest  play  of  light  upon  them,  and  permits  their  beauties  to  be  fully 
seen.  Jewels  set  in  this  way  are,  however,  in  greater  danger  of  being 
lost,  since  the  gem  cannot  be  quite  as  firmly  held  as  in  the  encased 
mount.  In  the  encased  mount  the  stone  is  set  in  a  metal  bed  with 
only  the  top  exposed.  This  mount  is  familiarly  seen  in  many  articles 
of  jewelry.  Being  cemented  to  the  metal  bed  the  stone  is  in  less 
danger  of  loss  or  injury  than  in  the  mount  a  jour.  With  the  encased 
mount  the  effect  of  the  stone  can  be  much  enhanced  by  the  use  of  foils 
and  paints,  and  many  defects  can  be  made  invisible.  Thus  black  specks 
in  a  stone  can  be  overcome  by  setting  against  a  black  background, 
while  a  gold  foil  serves  to  bring  out  the  fire  of  a  garnet,  for  example, 
as  an  a  jour  setting  could  not.  In  all  this  work  of  setting  gems  and 
overcoming  their  defects,  the  Oriental  peoples  especially  excel,  and 
have  done  so  for  centuries.  Examples  of  their  work  furnish,  as  a 
rule,  the  best  models  for  study. 


VALUATION  AND  PRICE 

The  unit  of  valuation  by  weight  of  gems  in  most  countries  is  the 
carat.  This  term  meant  originally,  according  to  some  authorities,  the 
weight  of  a  bean  of  the  coral  tree  (Ery 'thrina),  known  in  Africa  as  kuara, 
and  used  there  for  weighing  gold-dust.  Others  believe  the  term  to  be 
derived  from  the  Greek  word  keration,  said  to  be  the  name  of  the 
fruit  of  a  variety  of  acacia  having  seeds  of  remarkably  uniform  size. 
As  at  present  employed  the  weight  of  the  carat  expressed  in  grams 
is  about  one-fifth  of  a  gram  (200  milligrams),  but  varies  in  different 
countries  from  197  to  216  milligrams.  Th'e  accepted  weight  in  most 
of  the  large  gem  markets,  such  as  Paris,  London,  and  Berlin,  varies 
little  from  205  milligrams.  This  makes  a  carat  weight  a  little  over  3 
grains  troy,  the  exact  decimal  being  3.165.  Hence  one  grain  troy =0.3 16 
carat,  and  one  ounce  troy=151.7  carats.  The  weight  of  the  carat  is 
usually  given  as  four  grains  troy,  but  this  is  obviously  not  quite  correct. 
The  carat  is  subdivided  into  four  equal  parts,  also  known  as  grains,  which 
evidently  have  not  quite  the  weight  of  the  troy  grain,  although  the  two 
are  often  confounded.  The  balances  used  for  weighing  gems  are  usually 
divided  into  sixty-fourths,  and  the  fractional  parts  of  a  carat  weight  are 
then  expressed  by  series  of  common  fractions  rather  than  by  one  fraction 
or  a  decimal.  Thus  a  gem  weighing  3|f  carats  might  have  its  weight 
expressed  in  this  manner,  3^,  ^,  ^.  This  is  a  record  of  the  succes- 
sive divisions  of  the  scale  met  in  making  the  weight,  not  reduced  to 
a  simple  fraction. 

The  size  of  a  stone  of  a  given  number  of  carats  obviously  varies  with 
specific  gravity  of  the  gem;  a  two-carat  sapphire,  for  instance, being  a 
smaller  stone  than  an  emerald  of  the  same  weight.  The  size  of  diamonds 
of  different  carats  weight  is  shown  by  the  accompanying  cuts,  and  they 
represent  approximately  the  size  of  most  gems  of  the  same  number  of 
carats. 

The  size  of  a  stone,  besides  being  indicated  by  weight,  is  frequently 
expressed  by  a  number.  This  number  refers  to  a  scale  of  standard  sizes 
adopted  by  jewelers,  which  runs  from  1  to  50.  Thus  a  stone  of  the  size 
of  No.  12  in  the  scale  has  a  weight  of  one-eighth  of  a  carat,  No.  24  one- 
half  a  carat,  No.  38  two  carats,  and  so  on.  The  scale  thus  affords  a 

50 


means  of  distinguishing  smaller  differences  of  size  than  would  be  con- 
venient by  weight  alone. 

The  measurement  of  the  weight  of  pearls  differs  from  that  of  other 
gems  in  that  pearls  are  measured  by  their  weight  in  grains.  The  grain 
here  employed  is  not  the  troy  grain,  however,  but  four-fifths  of  it,  so 
that  four  troy  grains  are  equal  to  five  pearl  grains,  and  a  troy  ounce 
contains  600  pearl  grains. 

So  far  as  the  more  precious  gems  are  concerned,  it  may  be  noted  that 
their  price  increases  in  a  much  higher  proportion  than  does  the  weight. 
According  to  a  rule,  sometimes  called  Tavernier's  and  sometimes  Jeffries' 
rule,  the  price  should  increase  as  the  square  of  the  weight.  Thus  if  a 


Exact  sizes  of  diamond  brilliants  from  34  to  100  carats  weight 


carat  stone  is  worth  $80,  a  five-carat  stone  would  be  worth  not  five 
times  $80=$400,  but  52  or  25  times  $80=$2,000.  The  rule,  how- 
ever, affords  no  more  than  an  approximation  of  the  value,  it  giving  in 
general  too  high  a  result.  Some  gems,  such  as  amethyst,  topaz,  and 
others,  increase  in  value  only  in  about  the  same  proportion  as  they  increase 
in  weight,  since  large  stones  of  these  species  can  be  readily  obtained. 

In  addition  to  weight,  quality  is  a  factor  largely  affecting  the  price  of 
precious  stones.  To  be  of  the  first  quality,  or  first  water,  a  gem  must  be 
of  uniform  luster  and  color,  must  be  free  from  cracks  of  every  kind,  from 
bubbles,  and  if  transparent,  from  inclusions  of  every  sort,  cloudy  spots 
or  streaks.  Any  of  these  flaws  can  usually  be  distinguished  by  holding 
the  stone  between  the  eye  and  the  light,  or  they  are  more  clearly  brought 
out  if  the  stone  is  immersed  in  a  liquid  with  high  refractive  power,  such 
as  oil  of  cloves,  linseed  oil,  or  even  kerosene.  These  flaws  may  occur  in 
the  rough  stone,  or  the  operation  of  cutting  may  produce  little  cracks, 
called  feathers,  which  injure  the  value.  Obviously,  therefore,  to  be  sure 
of  obtaining  a  flawless  gem,  it  should  be  purchased  after  the  operation 
of  cutting  has  been  completed. 

The  value  of  rough  stones  compared  with  those  cut  varies  with  the 

51 


variety  and  size  of  the  stones.  Not  only  does  cutting  reduce  the  stone  in 
size,  but  the  cost  of  cutting  must  be  taken  into  consideration.  The  latter 
may  represent  almost  the  entire  value  of  stones  the  raw  material  of 
which  is  abundant  and  cheap,  as  is  true  of  many  of  the  varieties  of 
quartz.  In  the  case  of  diamonds  the  cost  of  cutting  adds  about  50$>  to 
their  value. 

The  price  of  gems,  besides  varying  with  quality  and  species,  is  de- 
pendent like  that  of  other  commodities  upon  supply  and  demand,  which 
are  in  turn  affected  by  discoveries  of  new  sources,  and  by  changes  of 
fashion.  Thus  the  discoveries  of  diamonds  in  Brazil  and  South  Africa 
respectively  caused  a  fall  in  the  prices  of  this  gem  at  each  of  these 
periods  because  of  the  increased  supply  afforded.  In  1750,  just  before 
the  influx  of  Brazilian  diamonds  into  Europe,  one-carat  stones  were 
valued  at  $40.  Shortly  after,  when  the  supply  from  Brazil  poured  into 
the  market,  they  fell  to  a  value  of  only  $5.  In  1791  this  price  had 
risen  to  $30.  This  fell  again  to  $20  during  the  French  wars  of  1848,  but 
by  1865  had  risen  to  nearly  $100,  which  is  not  far  from  the  present  price. 
At  the  present  time  the  emerald  has  reached  an  unprecedented  price, 
because  while  the  demand  is  steady  the  supply  has  almost  entirely  failed. 
On  the  other  hand,  the  sapphire  has  fallen  about  25$  in  value  in  the  last 
twenty  years  on  account  of  the  discovery  of  new  fields.  In  some  cases, 
however,  the  failure  of  supply  of  a  little-used  gem  may  cause  the 
demand  for  it  to  cease,  as  has  happened  with  the  Italian  diopside. 

The  price  of  the  four  gems,  diamond,  ruby,  sapphire,  and  emerald,  is 
on  the  whole  little  influenced  by  changes  of  fashion,  for  they  seem  to 
be  always  in  demand.  Most  of  the  other  gems,  however,  vary  in  price 
with  the  fashion,  being  at  one  time  much  in  vogue  and  again  almost  for- 
gotten. Thus  topaz  is  now  little  prized,  but  Kunz  states  that  the  mines 
of  this  gem  in  Spain  have  been  bought  and  are  being  held  by  a  French 
company  in  anticipation  of  a  return  of  the  stone  to  fashion.  This  might 
cause  a  demand  for  it  equal  to  that  of  forty  years  ago,  when  it  brought 
from  $4  to  $8  per  carat. 

As  gems  are  objects  of  luxury,  and  not  of  necessity,  the  demand  for 
them  is  greater,  and  hence  their  price  is  higher,  in  times  of  prosperity. 
Vice  versa  in  hard  times,  or  periods  of  financial  depression,  prices  of 
gems  fall.  The  period  following  the  French  Revolution  witnessed  a  great 
lowering  of  the  prices  of  gems,  partly  because  the  previous  extrava- 
gances of  the  French  court  in  this  direction  had  been  one  of  the  sources 
of  popular  discontent,  and  partly  because  of  the  general  financial  depres- 
sion. At  the  present  time  in  the  United  States  the  magnitude  of  the 
gem  trade  is  greater  than  ever  before. 


The  skill  with  which  a  stone  is  cut  should  be  taken  into  considera- 
tion in  valuing  it,  although  this  is  a  matter  upon  which  only  an  expert 
is  competent  to  give  an  opinion.  Of  two  stones  of  the  same  weight 
and  equal  quality,  one  may  be  worth  ten  times  as  much  as  the  other 
because  more  skilfully  cut.  Further,  the  exact  qualities  desirable  in 
any  particular  gem  are  points  to  be  learned  by  long  skill  and  experience, 
and  stones  possessing  these  qualities  command  much  higher  prices 
than  the  ordinary. 


53 


IMITATION   GEMS  AND   HOW  TO 
DETECT  THEM 

The  art  of  imitating  gems  has  reached  a  high  degree  of  perfection, 
and  while  the  substitutes  thus  prepared  have  legitimate  uses,  the  tempta- 
tion to  palm  them  off  on  the  unsuspecting  for  real  gems,  at  or  near 
the  price  of  the  genuine,  is  often  too  strong  to  be  resisted.  It  becomes 
important,  therefore,  that  every  one  purchasing  precious  stones  should 
be  acquainted  with  the  characteristics  of  the  false  as  well  as  of  the 
real,  and  unless  purchasing  of  a  perfectly  reliable  dealer  should  sub- 
ject the  offered  stone  to  the  most  careful  scrutiny.  Tourists  are  espe- 
cially liable  to  deception  of  this  sort,  since  their  purchases  must  be 
largely  made  of  itinerant  venders,  with  whom  they  are  not  acquainted. 
The  Persian  turquois  venders,  knowing  the  liability  of  some  of  their 
wares  to  fade,  are  accustomed  to  leave  for  parts  unknown  as  soon 
as  their  stock  is  disposed  of,  and  gem-sellers  of  other  nations  often 
exhibit  similar  propensities. 

Emanuel  tells  of  a  man  who  left  his  business  in  his  own  country, 
and  at  considerable  expense  went  to  England  to  sell  a  quantity  of  stones 
which  he  had  been  assured  were  diamonds,  only  to  find  on  arrival  there 
that  they  were  simply  quartz.  This  experience  in  one  form  or  another 
has  doubtless  been  repeated  countless  times,  and  should  serve  to  show 
the  importance  of  knowledge  on  the  part  of  all  purchasers  of  gems  of  the 
features  which  make  them  intrinsically  valuable. 

It  may  be  said  in  general  that  the  one  quality  of  most  gems  which 
cannot  be  successfully  duplicated  is  their  hardness.  The  best  simple 
protection  therefore  against  purchase  of  a  glass  imitation  for  most  precious 
stones  will  be  found  in  a  test  of  this  property.  Glass  is  softer  than 
most  precious  stones,  and  hence  is  much  more  easily  scratched  than 
they.  It  will  yield  to  the  file,  while  they  will  not.  This  test  should 
of  course  be  made  so  as  to  avoid  injury  of  the  stone,  for  often  the 
girdle  of  a  gem  cut  as  a  brilliant  is  as  delicate  as  a  knife  edge,  and 
great  care  should  be  used  in  testing  it.  If  a  file  be  not  convenient, 
a  fragment  of  quartz  can  usually  be  obtained,  and  affords  an  accurate 
means  of  testing  hardness,  since  the  hardness  of  quartz  is  7,  and  that 

54 


of  glass  rarely  over  5.  An  aluminum  pencil  also  affords  a  safe  means 
of  testing  hardness.  Drawn  over  glass  it  leaves  a  white,  silvery  line, 
but  on  hard  gems  little  if  any  mark.  In  respect  to  color,  luster,  and 
even  specific  gravity,  glass  may  be  made  to  imitate  almost  any  gem. 
Even  natural  looking  flaws  can  be  made  in  a  glass  imitation  by  dexter- 
ous hammer  blows.  Nevertheless  glass  can  often,  though  not  always, 
be  distinguished  from  a  mineral  by  the  fact  that  in  a  piece  of  glass 
minute  air  bubbles  may  be  seen  on  examining  it  with  a  lens.  These 
bubbles  generally  differ  in  shape  and  number  from  any  found  in  natural 
minerals.  Glass  also  has  a  characteristic  conchoidal  fracture  not  quite 
like  that  usual  to  minerals.  Jj'ue  gems  are  colder  to  the  touch  than 
glass  as  a  rule,  although  glass  is  colder  than  such  substances  as  jet, 
amber,  and  pearl,  for  which  it  is  often  substituted.  The^colder  feeling 
of  true  gems  comes  from  their  being  better  conductors  of  heat  than  glass, 
so  that  they  take  away  warmth  from  the  hand  more  rapidly.  For  the 
same  reason  most  true  gems  when  breathed  upon  acquire  a  thicker  coat-, 
ing  of  moisture  than  glass  and  lose  it  more  quickly  than  does  that  sub- 
stance. In  the  application  of  these  simple  tests  jewelers  often  become 
very  skilful,  and  if  the  stones  are  not  too  small  can  pick  out  a  diamond, 
sapphire,  or  other  gem  from  a  whole  bagful  of  glass  imitations  by  the 
above  distinctions  alone.  When  in  the  rough,  a  useful  distinction  of 
glass  from  most  gems  is  to  be  found  in  the  easy  fusibility  of  the  former 
before  the  blowpipe.  While  most  gems  are  practically  infusible  in  this 
way,  glass  is  easily  fused,  and  hence  the  trial  of  a  splinter  of  the  sub- 
stance before  the  blowpipe  affords  a  test  of  value.  The  distinction  of 
glass  from  minerals  by  an  observation  of  their  behavior  in  polarized  light 
can  be  made  without  injury  to  the  substance  tested,  and  with  reliable 
results.  To  be  sure,  the  distinction  of  glass  from  diamond,  spinel-ruby, 
or  other  singly  refracting  gem,  cannot  be  made  in  this  way ;  but  when 
the  stone  is  doubly  refracting,  as  is  the  case  with  the  majority  of  species, 
such  investigation  affords  one  of  the  surest  and  most  convenient  means 
of  identification.  The  use  of  the  dichroscope  or  polarizing  microscope 
for  this  purpose  has  already  been  explained. 

The  glass  used  for  making  imitation  gems  is  usually  one  having  a 
high  percentage  of  lead  in  its  composition.  The  lead  makes  it  soft  but 
gives  it  great  brilliancy.  The  glass  is  usually  known  as  paste,  or  strass, 
the  latter  name  being  from  the  inventor,  Strass  of  Strassburg,  who 
invented  the  mixture  during  the  seventeenth  century.  Uncolored  it 
affords  a  good  imitation  of  the  diamond,  and  when  colored  with  various 
metallic  oxides,  remarkably  accurate  likenesses  of  different  gems  can  be 
obtained. 

55 


Besides  counterfeits  wholly  of  glass,  many  precious  stones  are  adul- 
terated, so  to  speak,  by  making  a  portion  of  a  genuine  stone,  and 
employing  glass  for  the  remainder.  Such  fabrications  are  called 
doublets,  the  upper  part  of  the  stone  being  of  course  the  genuine 
portion.  The  application  of  a  file  to  the  upper  and  lower  parts  in 
turn  will  usually  detect  the  fraud;  or  if  the  two  parts  are  cemented 
together  by  gum  mastic,  as  is  usually  done,  they  will  separate  on 
being  soaked  in  warm  water.  The  union  can  also  often  be  seen  on 
holding  the  cemented  stone  up  to  the  light.  Occasionally,  however, 
the  two  are  fused  together,  in  which  case  soaking  would  not  separate 
them,  nor  would  the  plane  of  union  be  visible.  A  desired  color  is  some- 
times given  to  doublets  by  inserting  a  foil  between  the  two  portions. 

Besides  the  use  of  glass  in  place  of  precious  stones,  an  effort  is 
often  made  to  substitute  a  cheaper  stone  for  the  one  represented. 
Quartz,  white  sapphire,  and  topaz  may  thus  be  substituted  for  diamond, 
pink  topaz  for  ruby,  and  so  on.  In  such  cases  the  distinction  of  hard- 
ness is  not  as  marked  as  if  glass  is  employed;  but  the  test  with  light 
can  usually  be  made,  and  determination  of  the  specific  gravity,  or  other 
property,  often  serves  to  detect  the  counterfeit. 

Besides  employing  the  above-named  devices,  deception  is  sometimes 
achieved  by  making  a  large  stone  of  two  smaller  ones  of  the  same 
mineral  cemented  together.  Again,  inferior  stones  may  have  their  backs 
painted  to  give  them  a  desired  color.  The  practice  of  setting  a  stone 
against  a  foil  in  order  better  to  bring  out  its  color  or  luster  —  as,  for 
instance,  mounting  an  opal  or  moonstone  on  black,  or  garnet  against 
silver  —  is  not  considered  illegitimate,  and  should  by  all  means  be 
employed  when  the  effect  of  a  stone  can  thus  be  enhanced. 

The  difficulties  of  detecting  fraudulent  gems  will  obviously  be  greatly 
increased  if  the  stones  are  set.  Gems  should,  therefore,  always  be  pur- 
chased loose  if  possible,  especially  costly  ones. 

On  the  whole,  the  accurate  distinction  of  gems,  or  detection  of  frauds, 
requires  knowledge  of  the  different  physical  characters  of  each  species, 
such  as  hardness,  specific  gravity,  and  behavior  in  polarized  light. 
A  single  test  is  rarely  sufficient  to  identify  a  gem;  but  by  the  use 
of  several,  perfectly  trustworthy  results  can  be  obtained. 


56 


SUPERSTITIONS  REGARDING   GEMS 

From  the  earliest  times  and  among  all  peoples  there  seem  to  have 
been  sentiments  and  superstitions  connected  with  gems.  Not  only 
was  the  power  of  driving  away  evil  spirits  and  producing  all  sorts 
of  "  luck "  long  attributed  to  themv  but  as  late  as  the  beginning 
of  the  eighteenth  century  reputable  physicians  were  accustomed  to  mix 
fragments  of  them  in  their  medicines  and  to  use  them  as  charms.  /To 
this  day  amber  is  kept  in  stock  by  druggists  in  Paris  for  use  in  filling 
prescriptions.  xThe  Chinese  still  use  powdered  pearls,  coral,  and  other 
gems  in  medicine,  and  various  Indian  tribes  of  North  America  ascribe 
great  medicinal  value  to  one  gem  or  another.  In  the  writings  of  Greek 
and  Roman  writers  are  found  many  statements  indicating  belief  in 
the  medicinal  and  other  virtues  of  gems.  It  was  in  the  Middle  Ages, 
however,  that  these  opinions  seem  to  have  been  most  widely  and  firmly 
held,  so  far  as  it  is  possible  to  learn  of  them  through  history. 

The  following  passage  from  Marbodus,  a  writer  of  the  latter  part 
of  the  eleventh  century,  is  a  good  example  of  some  of  the  virtues 
attributed  to  gems  in  that  time:* 

"The  chalcedony,  if  blest  and  tied  round  the  neck,  cures  lunatics. 
Moreover,  he  that  wears  it  will  never  be  drowned  or  tempest-tossed. 
It  also  makes  the  wearer  beautiful,  faithful,  strong,  and  successful  in 
all  things.  One  ought  to  engrave  upon  it  Mars  armed,  and  a  virgin 
robed,  wrapped  ha  a  vestment,  and  holding  a  laurel  branch;  with  a  per- 
petual blessing. 

'•Aristotle,  in  his  book  on  gems,  says  that  an  ^emerald  hung  from 
the  neck,  or  worn  on  the  finger,  protects  against  danger  of  the  falling 
sickness.  We  therefore  commend  noblemen,  that  it  be  hanged  about 
the  necks  of  their  children  that  they  fall  not  into  this  complaint. 
The  emerald  is  approved  in  all  kinds  of  divination;  in  every  busi- 
ness if  worn  it  increases  its  owner's  importance,  both  in  presence  and 
in  speech. 

"A  sard,  of  the  weight  of  twenty  grains  of  barley,  if  hung  round 
the  neck  or  worn  on  the  finger,  the  wearer  shall  not  have  terrible 

*  King,  Antique  Gems,  p.  432. 

57 


or   disagreeable   dreams,   and   shall   have   no   fear  of   incantations   or 
of  witchcraft. 

"The  beryl  is  a  large  and  transparent  stone.  Engrave  upon  it 
a  lobster,  and  under  its  legs  a  raven,  and  put  under  the  gem  a  vervain 
leaf,  inclosed  in  a  little  plate  of  gold;  it  being  consecrated  and  worn, 
makes  the  wearer  conqueror  of  all  bad  things,  and  gives  protection 
against  all  diseases  of  the  eyes.  And  if  you  put  this  stone  in  water, 
and  give  this  water  to  one  to  drink,  it  cures  stoppage  of  the  breath 
and  hiccups,  and  dispels  pains  of  the  liver.  It  is  useful  to  be  worn,  and 
he  that  hath  this  gem  upon  him  shall  be  victorious  in  battle  over  all  his 
foes.  It  is  found  in  India,  like  unto  the  emerald,  but  of  a  paler  cast. 

"The  sard  is  good  to  be  worn,  and  makes  the  person  beloved  by 
women;  engrave  upon  it  a  vine  and  ivy  twining  round  it. 

"The  casteis  (callais  turquois)  is  good  for  liberty,  for  he  that  hath 
consecrated  it,  and  duly  performed  all  things  necessary  to  be  done  in 
it,  shall  obtain  liberty.  It  is  fitting  to  perfect  the  stone  when  you  have 
got  it,  in  this  manner :  Engrave  upon  it  a  beetle,  then  a  man  standing 
under  it;  afterwards  let  it  be  bored  through  its  length  and  set  on 
a  gold  fibula  (swivel);  then  being  blest  and  set  in  an  adorned  and 
prepared  place,  it  will  show  forth  the  glory  which  God  hath  given  it." 

Some  of  the  other  traditional  virtues  of  gems  ascribed  chiefly  in 
the  Middle  Ages,  but  many  doubtless  of  earlier  origin,  are  as  follows : 

Agate  was  believed  to  have  the  power  of  averting  storms,  counter- 
acting poison,  and  stemming  the  flow  of  blood.  A  black  agate  with 
white  veins  was  considered  a  potent  talisman  against  every  danger, 
and  to  have  the  power  of  rendering  the  wearer  invisible. 

Amber  worn  in  beads  about  the  neck  or  wrist  was  regarded  a  cure 
for  sore  throat  and  ague,  and  a  preventive  of  insanity,  asthma,  dropsy, 
toothache,  and  deafness. 

The  bloodstone  prevented  death  from  bleeding. 

The  cat's-eye  warned  its  wearer  of  danger,  storms,  and  troubles, 
and  was  a  charm  against  witchcraft.  It  was  also  a  cure  for  croup  when 
applied  locally. 

Precious  coral  prevented  blight,  caterpillars,  storms,  and  locusts, 
and  was  a  charm  against  lightning,  whirlwind,  shipwreck,  and  fire. 
Taken  internally  it  was  a  cure  for  indigestion. 

The  diamond  was  a  talisman  against  danger,  and  gave  hardiness, 
fortitude,  and  manhood  to  its  owner. 

The  emerald  gave  immortality,  won  the  favor  of  rulers  and  paci- 
fication of  enemies.  If  its  wearer  was  unmarried  it  rendered  him 
invisible. 

58 


The  garnet  was  a  preventive  of  fever  and  dropsy,  and  rendered 
its  wearer  agreeable,  powerful,  and  victorious. 

The  hyacinth  gave  second  sight,  promoted  sleep,  and  preserved 
from  thunderstorms  and  pestilences. 

lolite  foretold  storms  by  changing  hue. 

Jasper  had  the  power  of  stopping  overflowing  blood,  or  water,  and 
was  a  preventive  of  poison. 

Jet  induced  fertility. 

Moonstone  was  believed  to  contain  an  image  of  the  moon,  which 
grew  clear  upon  days  and  occasions  fortunate  to  its  owner,  and  dim 
with  the  reverse.  It  was  thought  to  wax  and  wane  with  the  moon 
and  was  a  cure  for  epilepsy. 

The  onyx  exposed  its  wearer  to  lawsuits,  bad  dreams,  and  demons. 
If  a  sard  were  worn  with  it,  however,  these  evil  influences  were  counter- 
acted. It  symbolized  and  insured  conjugal  felicity. 

The  opal  faded  upon  the  insincere,  deceitful,  and  impure ;  but  when 
worn  by  the  innocent  united  the  special  virtues  of  all  gems. 

The  pearl  insured  entrance  to  Heaven;  but  this  privilege  might 
be  lost  by  carelessness  of  life. 

Quartz  if  burned  averted  storms,  and  powdered  and  mixed  with 
water  cured  serpents'  bites. 

The  ruby  preserved  its  owner's  house  or  vineyard  from  lightning, 
tempest,  and  worms  if  the  former  were  touched  by  it.  It  was  also 
a  disinfectant  and  preventive  of  infectious  diseases.  Bruised  in  water 
it  relieved  weakness  of  the  eyes,  and  cured  liver  complaints. 

The  sapphire  was  a  preventive  of  despair  and  fire;  a  curative 
of  madness  and  boils. 

The  topaz  was  good  for  burns,  and  if  thrown  into  boiling  water 
deprived  it  of  its  heat.  It  prevented  melancholy  and  cured  hemor- 
rhages. Its  internal  brilliancy  was  believed  to  follow  the  phases 
of  the  moon. 

Tourmaline  when  heated  was  capable  of  charming  away  pain,  such 
as  toothache,  headache,  etc. 

A  turquois  grew  pale  if  its  owner  became  sick,  and  lost  its  color 
at  death  until  placed  upon  a  princess's  finger.  It  prevented  injury 
in  case  of  a  fall.  Held  suspended  in  a  glass  it  told  the  hour  by 
strokes  against  the  sides.  It  was  a  cheerer  of  the  soul  and  insured 
prosperity. 

Such  opinions  regarding  the  virtues  of  gems  were  not  confined  to  the 
lower  classes  but  were  held  generally.  There  is  little  doubt  that  rulers 
were  accustomed  to  carry  their  gems  to  the  battle-field  with  them  for  the 

59 


sake  of  the  protection  they  might  afford  and  victory  they  might  give, 
for  Charles  the  Bold  lost  his  gems,  among  which  is  said  to  have 
been  the  Florentine  diamond,  at  the  battle-field  of  Nancy  in  this  way, 
and  there  are  other  instances  indicating  that  the  practice  of  carrying 
•gems  for  this  purpose  was  common. 


60 


BIRTH-STONES 

Another  interesting  illustration  of  the  regard  in  which  precious 
stones  have  been  held  is  the  custom,  which  survives  to  some  extent  to 
the  present  day,  of  making  a  particular  gem  appropriate  to  a  certain 
month  of  the  year. 

Perhaps  the  first  arrangement  of  gems  into  a  group  of  twelve  of 
which  we  have  any  record  is  that  in  the  Book  of  Exodus.  Here  in  the 
twenty-eighth  chapter,  verses  17-19,  are  prescribed  in  order  twelve 
precious  stones,  which  shall  be  set  in  the  breastplate  of  the  high 
priest.  The  list  is  repeated  in  the  thirty-ninth  chapter  of  the  same 
book,  verses  10-12.  In  the  context  it  is  prescribed  that  the  stones 
shall  be  set  in  four  rows,  and  that  upon  them  shall  be  engraved  the 
names  of  the  children  of  Israel,  one  for  each  stone.  As  to  the  par- 
ticular gems  which  are  indicated  by  the  Hebrew  words,  authorities 
differ;  but  in  the  Authorized  Version  of  the  Bible  they  are  given  as 
follows : 

Sardius,  topaz,  carbuncle, 

Emerald,  sapphire,  diamond, 

Ligure,  agate,  amethyst, 

Beryl,  onyx,  jasper. 

It  is  not  probable,  however,  that  these  names  indicate  in  each  case 
the  corresponding  stones  of  modern  usage.  Thus,  it  is  quite  unlikely 
that  the  Hebrews  could  have  engraved  a  name  upon  the  diamond 
even  if  they  could  have  obtained  one  of  sufficient  size.  Again,  the 
words  emerald  and  carbuncle  are  undoubtedly  interchanged  in  the 
above  list,  and  the  ancient  topaz  is  known  to  have  been  the  modern 
chrysolite.  In  the  Revised  Version  the  word  jacinth  is  substituted  for 
ligure,  and  amber  is  given  as  a  marginal  rendering  for  the  same.  There 
are  also  given  marginal  renderings  for  others  of  the  gems  as  follows: 
Ruby  for  sardius,  emerald  for  carbuncle,  carbuncle  for  emerald,  sardonyx 
for  diamond,  chalcedony  for  beryl,  and  beryl  for  onyx.  The  modern 
equivalents  of  the  terms  recognized  by  secret  orders  which  use  them 
in  symbolism  are: 


61 


Carnelian,  chrysolite,  emerald, 
Ruby,  lapis-lazuli,  onyx, 
Sapphire,  agate,  amethyst, 
Topaz,  beryl,  jasper. 

Two  lists  of  precious  stones,  quite  similar  to  those  of  the  Book  of  Exo- 
dus, are  given  in  other  places  in  the  Bible,  one  in  Ezekiel  xxviii.  13, 
where  "  every  precious  stone  "  is  said  to  have  been  the  covering  of  the 
king  of  Tyre,  and  again  in  Revelation  xxi.  19-20,  where  twelve  differ- 
ent precious  stones  are  mentioned  as  garnishing  the  foundations  of  the 
wall  of  the  Holy  City.  The  names  and  order  of  these  in  Ezekiel  are, 
in  the  Authorized  Version,  as  follows : 

Sardius,  topaz,  diamond, 
Beryl,  onyx,  jasper, 
Sapphire,  emerald,  carbuncle. 

To  these  the  Septaguint  adds  the  following: 
Chrysolite,  ligure,  agate. 

The  Revised  Version  gives  marginally,  ruby  for  sardius,  carbuncle 
for  emerald,  and  emerald  for  carbuncle.  In  Revelation  the  list  as 
given  in  the  Authorized  Version  reads  as  follows: 

Jasper,  sapphire,  chalcedony, 
Emerald,  sardonyx,  sardius, 
Chrysolite,  beryl,  topaz, 
Chrysoprase,  jacinth,  amethyst. 

The  marginal  renderings  give  lapis-lazuli  for  sapphire,  and  sapphire 
for  jacinth. 

Though  in  each  of  these  lists  only  twelve  precious  stones  are  men- 
tioned, there  is  nothing  to  indicate  that  their  use  was  in  any  way 
connected  with  the  months  of  the  year.  Just  when  it  became  the 
custom  to  designate  each  month  by  a  particular  gem,  or  how  the 
custom  originated,  it  is  impossible  to  determine.  The  custom  seems  to 
have  sprung  up  in  modern  Europe  some  time  during  the  fifteenth  or 
sixteenth  century.  Whether  it  originated  in  the  twelve  gems  of  Aaron's 
breastplate,  as  many  believe,  or  was  introduced  by  astrologers  from  the 
Arabians,  as  others  think,  is  not  yet  known. 

The  modern  practice  of  considering  the  stone  of  each  month  espe- 
cially appropriate  to  persons  born  in  that  month  is  probably  still  more 
recent  in  its  origin.  In  former  times  gems  could  be  possessed  only 
by  rulers  or  the  very  wealthy,  so  that  their  general  use  in  the  above 
manner  was  not  possible.  But  now  that  nearly  every  one  can  own 

62 


a  gem  of  some  kind,  the  possession  of  "birth-stones,"  and  the  attach- 
ment of  special  sentiments  to  them,  has  become  common.  The  custom 
is  a  pretty  one,  and  is  to  be  commended,  for  the  stones  are  imperish- 
able, and  the  sentiments  ascribed  to  them  represent  the  accumulated 
traditions  of  many  ages,  races,  and  peoples. 

As  to  the  particular  stone  which  is  to  be  considered  appropriate 
to  each  month  usages  differ.  Such  differences  have  doubtless  arisen 
from  the  desire  to  introduce  gems  which  were  formerly  little  known 
or  unattainable  on  account  of  their  cost,  as  substitutes  for  stones  for- 
merly prized  but  now  held  of  little  value.  Thus  the  precious  opal, 
now  within  the  reach  of  all,  was  rare  in  former  times.  By  some  it 
is  now  used  as  the  birth-stone  of  the  month  of  October,  while  others 
retain  the  beryl.  The  diamond  has  been  introduced  in  modern  practice 
in  quite  a  similar  way.  The  carnelian  and  chrysolite,  by  some  still 
used  for  the  months  of  August  and  September,  are  stones  held  of  little 
worth  at  present,  and  hence  others  are  usually  substituted.  The  par- 
ticular order  and  kind  of  stones  adopted  in  the  colored  plate  which  serves 
as  a  frontispiece  to  this  work  is  given  in  accordance  with  some  verses 
quoted  in  a  pamphlet  first  published  by  Tiffany  &  Company,  of  New 
York,  in  1870.  The  author  of  the  verses  is  not  known,  nor  is  it  known 
by  just  what  authority  these  gems  were  chosen.  The  choice,  however, 
seems  as  satisfactory  as  could  be  made. 

JANUARY 

By  her  who  in  this  month  is  born, 
No  gems  save  garnets  should  be  worn; 
They  will  insure  her  constancy, 
True  friendship,  and  fidelity. 

FEBRUARY 

The  February-born  shall  find 
Sincerity  and  peace  of  mind, 
Freedom  from  passion  and  from  care, 
If  they  an  amethyst^  will  wear. 

MARCH 

Who  in  this  world  of  ours  their  eyes 
In  March  first  open  shall  be  wise, 
In  days  of  peril  firm  and  brave, 
And  wear  a  bioodstone  to  their  grave. 

APRIL 

She  who  from  April  dates  her  years, 
Diamonds  shall  wear,  lest  bitter  tears 
For  vain  repentance  flow;  this  stone, 
Emblem  of  innocence,  is  known. 
63 


MAY 


v      WhQ  first  beholds  the  light  of  day 

In  spring's  sweet  flowery  month  of  May, 
And  wears  an  emerald  all  her  life, 
Shall  be  a  loveoancThappy  wife. 


JUNE 


Who  comes  with  summer  to  this  earth, 
And  owes  to  June  her  hour  of  birth, 
With  ring  of  agate  on  her  hand 
Can  health,  weaMi,  and  long  life  command. 


JULY 


The  glowing  ruby  shall  adorn 
Those  who  in  July  are  born; 
Then  they'll  be  exempt  and  free 
From  love's  doubts  and  anxiety. 


AUGUST 


Wear  a  sardonyx,  or  for  thee 

No  conjugat~felicity; 

The  August-born  without  this  stone, 

'Tis  said,  must  live  unloved  and  lone. 


SEPTEMBER 


A  maiden  born  when  September  leaves 
Are  rustling  in  September's  breeze, 
A  sapphire  on  her  brow  should  bind  — 
'Twill  cure  diseases  of  the  mind. 

OCTOBER 

October's  child  is  born  for  woe, 
And  life's  vicissitudes  must  know; 
But  lay  an  opal  on  her  breast, 
And  hope  will  lull  those  woes  to  rest. 

NOVEMBER 

Who  first  comes  to  this  world  below 
With  drear  November's  fog  and  snow, 
Should  prize  the  topaz's  amber  hue  — 
Emblem  of  friends  and  lovers  true. 

DECEMBER 

If  cold  December  gave  you  birth, 
The  month  of  snow  and  ice  and  mirth, 
Place  on  your  hand  a  tmquois-  blue ; 
Success  will  bless  whate'er  you  do. 
64 


Other  groupings  of  precious  stones  in  lists  of  twelve  are  those 
which  assign  one  to  each  of  the  twelve  tribes  of  Israel  and  to  the 
twelve  apostles.  The  list  of  the  former  is  thus  given  by  Alcott: 


Naphtali 
Asher     - 
Dan   - 
Gad 
Simeon 
Reuben 


Jasper. 

Onyx. 

Beryl. 

Diamond. 

Sapphire. 

Emerald. 


Benjamin   - 
Maiiasseh 
Ephraim     - 
Zebulon 
Issachar 
Judah    - 


Amethyst. 

Agate. 

Ligure. 

Garnet. 

Topaz. 

Euby. 


Tassin  however  gives  a  somewhat  different  list  obtained  from  an  old 
silver  breastplate  employed  as  an  ornament  for  a  manuscript  copy  of  the 
Torah,  or  Pentateuch,  used  in  an  ancient  synagogue  and  now  in  the  U. 
S.  National  Museum.  This  is  as  follows: 


Naphtali 

-    Agate 

Benjamin     - 

-    Jasper 

Asher 

Beryl 

Joseph    - 

Onyx 

Dan     ... 

-    Topaz 

Levi    - 

-    Garnet 

Gad 

Amethyst 

Zebulon  - 

Diamond 

Simeon  . 

-     Chrysolite 

Issachar 

-     Sapphire 

,    Reuben  - 

Sard 

Judah 

Emerald 

The  list  of 

the   gems   of   the 

twelve   apostles 

is   thus   given   by 

Emanuel  : 

Peter      - 

-     Jasper. 

Matthew 

-     Chrysolite. 

Andrew 

Sapphire. 

Thomas 

Beryl. 

James     - 

-     Chalcedony. 

Thaddeus 

-     Chrysoprase. 

John 

Emerald. 

James  the  Less  - 

Topaz. 

Philip     - 

-     Sardonyx. 

Simeon  - 

-     Hyacinth. 

Bartholomew 

k 

Cornelian. 

Matthias     - 

Amethyst. 

65 


DIAMOND 

The  diamond  is  generally  conceded  to  be  the  most  beautiful  as  it 
is  the  most  important  of  precious  stones.  A  few  other  stones  exceed 
it  in  value,  weight  for  weight;  but  in  total  importance  as  an 
article  of  commerce  other  gems  are  hardly  to  be  compared  with 
it.  Out  of  thirteen  and  one-half  millions  of  dollars'  worth  of  precious 
stones  imported  into  the  United  States  in  1900,  twelve  million  dollars' 
worth  were  diamonds.  Not  all  this  amount  was  employed  for  jewelry, 
since  there  is  a  large  utilization  of  the  stone  for  industrial  purposes; 
but  even  for  jewelry  the  diamond  has  a  largely  preponderating  use. 
Its  points  of  superiority  are  its  hardness,  its  high  refractive  powers, 
and  its  adamantine  luster.  In  all  these  qualities  it  excels  any  other 
known  mineral.  When  in  addition  to  these  it  exhibits  different  body 
colors,  as  is  sometimes  the  case,  the  most  highly  prized  of  gems  are 
produced. 

In  composition  the  diamond  is  pure  carbon,  thus  not  differing  chem- 
ically from  graphite,  or  such  forms  of  carbon  as  lamp-black,  bone-black, 
etc.  It  is  crystallized,  but  this  can  be  said  of  graphite  as  well.  Why 
carbon  should  assume  the  form  of  diamond  in  one  case  and  graphite 
in  another,  as  well  as  being  amorphous  in  other  occurrences,  is  not 
known.  Such  behavior  of  a  substance  is  known  as  dimorphism,  and 
numerous  illustrations  of  it  are  to  be  found  in  nature. 

Being  pure  carbon,  diamond  can  be  burned  in  the  air.  The  finely 
divided  dust  can  be  burned  in  the  ordinary  blow-pipe  flame,  and  for 
stones  of  ordinary  size  a  temperature  of  about  900°  C.  is  sufficient. 
The  possibility  of  consuming  the  diamond  by  heat  is  said  first  to  have 
been  suggested  by  Sir  Isaac  Newton,  who  reasoned  from  the  high 
refractive  index  of  the  stone  that  it  was  "  an  unctuous  substance 
coagulated,"  and  hence  probably  combustible.  Following  this  sugges- 
tion two  Italians,  Averani  and  Targioni,  succeeded,  in  1695,  in  burning 
some  diamonds  in  a  furnace,  and  since  then  the  experiment  has  been 
repeated  many  times.  The  diamond  does  not  fuse  in  burning,  but 
after  becoming  heated  to  redness  gradually  grows  smaller,  emitting 
sparks,  till  it  entirely  disappears.  It  leaves  no  ash,  except  in  the 
case  of  the  impure  form  known  as  carbonado.  The  gas  given  off  has 

66 


been  collected  and  analyzed,  and  found  to  be  carbon  dioxide,  just  as 
would  result  from  the  combustion  of  other  forms  of  carbon.  If  pro- 
tected from  the  air  or  free  oxygen,  the  diamond  can  be  exposed  to 
high  heat  without  change. 

Being  a  crystallized  substance  and  excessively  hard,  the  diamond 
is  usually  found  in  the  form  of  more  or  less  perfect  crystals.  These 
have  forms  such  as  the  cube,  octahedron,  etc.,  which  belong  to  the 
isometric  system,  and  it  is  in  this  system  that  the  diamond  crystal- 
lizes. The  crystals  do  not  possess,  however,  the  highest  isometric  sym- 
metry, but  belong  to  the  class  designated  by  Groth  as  hexakistetrahedral, 
being  tetrahedral  with  in-  clined  face  hemihedrism. 

Of  the  forms  occurring,  the  /X'\xv  octahedron,    which   is  the 

first  shown  in  the  accom-  /  V\  panying  cut,  is  best  suited 
for  cutting.  It  is  very  /_^^  V^  common  for  the  faces  to 
be  curved  instead  of  flat,  \  //  an(^  ^°  snow  etching 

figures  of  various  kinds.  \.  //  The  crystals  are  often  con- 
siderably distorted  so  as  ^^  to  produce  pointed  and 


Common  forms  of  diamond  crystals 

rounded  forms,  and  twin  crystals  are  common.  Although  so  excessively 
hard,  the  edges  of  the  crystals,  as  found  in  the  beds  of  streams,  are 
often  rounded  from  the  wear  of  the  other  pebbles,  probably  chiefly 
quartz.  Only  the  wear  of  centuries  could  produce  such  a  result,  how- 
ever; for,  as  is  well  known,  it  is  only  with  its  own  dust  that  the 
diamond  can  be  abraded  to  any  appreciable  degree  by  any  of  the 
means  now  used  for  cutting  it. 

One  important  property  of  crystallized  diamond  is  that  of  cleavage 
parallel  to  the  faces  of  the  octahedron.  This  cleavage  is  of  much 
service  in  preparing  the  gem  for  cutting,  as  by  taking  advantage 
of  it,  broad,  flat  surfaces  can  be  obtained  without  grinding.  This 
property  also  distinguishes  diamond  from  quartz,  for  which  its  crys- 
tals, as  found  in  sands,  are  sometimes  mistaken.  Quartz  has  no  cleav- 
age. The  fracture  of  the  two  minerals  is  the  same  however,  being 
conchoidal. 

The  massive  forms  of  the  diamond  known  as  bort  and  carbonado 

67 


possess  little  or  no  cleavage,  thus  increasing  their  value  as  abrasives 
and  for  setting  in  drills,  saws,  etc.  The  true  bort  occurs  as  rounded 
forms  made  up  of  a  confused  aggregate  of  crystals,  and  is  harder  than 
ordinary  diamond.  Fragments  of  crystals  of  no  value  as  gems,  or  any 
crude  diamond  dust,  are  also  known  as  bort  in  trade.  Carbonado 
is  a  name  given  to  black  diamond,  which  has  more  or  less  crystal- 
line structure.  This  graduates  into  the  crystallized  mineral.  Either 
of  these  is  more  valuable  than  the  crystallized  diamond  for  industrial 
purposes,  although  of  no  value  as  gems. 

Usually  the  diamond  is  colorless  or  white,  although  shades  of  yellow 
are  also  common.  It  is  also  known  in  shades  of  red,  green,  and  blue, 
and  in  brown  and  black.  The  two  latter  are  rarely  transparent,  and 
grade  into  bort  and  carbonado. 

About  half  the  diamonds  found  are  tinged  to  some  degree.  If  the 
color  is  but  slight,  the  stone  is  considered  less  valuable  than  if  per- 
fectly colorless;  but  a  diamond  of  pronounced  color  is  the  most  valu- 
able gem  known. 

Among  colors  of  diamonds,  blue  is  the  rarest.  The  largest  and 
most  valuable  colored  diamond  known  is  the  Hope  Blue,  weighing 
44£  carats.  This  is  valued  at  about  one  hundred  thousand  dollars. 
It  has  a  brilliant  deep  blue  color  and  is  without  a  flaw.  A  deep  blue 
diamond,  weighing  67^  carats,  was  long  worn  in  the  French  crown, 
but  it  was  stolen  in  1792  and  has  never  been  recovered.  Red  diamonds 
vary  in  hue  from  ruby-red  to  rose,  the  latter  being  the  most  common. 
No  large  red  diamonds  are  known,  the  largest  being  one  of  32  carats 
in  Vienna.  Another  famous  one  is  that  in  the  Russian  treasury, 
for  which  Paul  I.  paid  one  hundred  thousand  roubles.  It  is  of  a  ruby 
color.  The  finest  green  diamond  known  is  the  "Dresden  Green"  pre- 
served in  the  Green  Vaults  of  Saxony.  It  was  purchased  by  August  the 
Strong  in  1743  for  sixty  thousand  dollars.  It  is  apple-green  in  color 
and  weighs  40  carats.  Diamonds  of  yellow  color  are  comparatively 
common,  many  of  the  Cape  diamonds  being  lowered  in  value  by  possess- 
ing a  yellow  tinge.  It  is  said  that  this  injurious  yellow  tinge  can  be 
overcome  by  dipping  the  stone  several  times  in  a  solution  of  potas- 
sium permanganate,  the  violet  color  of  the  latter  neutralizing  the  yellow 
of  the  diamond.  The  yellow  tinge  usually  also  disappears  in  artificial 
light.  Of  large  diamonds  possessing  a  yellow  color  the  Florentine  and 
the  Tiffany  are  the  best  known.  The  color  of  colored  diamonds  is  gen- 
erally permanent,  but  that  of  some  is  said  to  fade  on  exposure  to  light. 
It  can  also  be  destroyed  or  changed  by  heat. 

The  luster  of  the  diamond  is  a  peculiar  one,  and  such  as  is  possessed 


by  few  other  minerals.  In  reference  to  its  occurrence  in  the  diamond 
it  is  known  as  the  adamantine  luster.  It  combines  the  peculiarity 
of  an  oily  luster  with  that  of  glass  and  that  of  a  metal.  It  is  doubt- 
less due  to  the  high  refractive  power  of  the  mineral,  which  causes 
more  than  the  ordinary  number  of  rays  of  light  to  come  to  the  eye. 
In  the  impure  forms  of  diamond  the  greasy  or  oily  luster  becomes 
more  pronounced.  Once  the  eye  becomes  accustomed  to  the  peculiar 
luster  of  diamond  the  stone  may  easily  be  distinguished  by  it  from 
glass  or  minerals  with  a  vitreous  luster,  such  as  quartz.  Certain  other 
minerals,  however,  such  as  cerussite,  zircon,  and  to  some  extent  sphene, 
exhibit  the  adamantine  luster.  In  the  glass  known  as  strass,  used 
to  make  imitation  diamonds,  the  adamantine  luster  is  well  reproduced. 

Diamond  is  usually  transparent,  but  it  may  be  translucent,  and  even 
opaque,  especially  the  black  varieties.  Even  otherwise  transparent 
diamond  often  contains  inclusions  which  cloud  and  interrupt  its  clear- 
ness. These  constitute  the  "flaws"  which  so  often  injure  the  value 
of  a  diamond  and  prevent  it  from  being  of  the  "  first  water."  These 
inclusions  may  be  simply  small  cavities,  sometimes  so  numerous  as 
to  make  the  stone  nearly  black;  or  they  may  be  particles  of  other 
minerals,  such  as  chlorite,  hematite,  or  carbonaceous  matter.  If  the 
latter,  the  flaws  can  sometimes  be  burned  out  by  careful  heating. 

As  already  remarked,  the  refractive  power  of  the  diamond  is  very 
high.  The  rays  of  light  entering  it  are  bent  at  a  high  angle,  causing 
a  large  degree  of  what  is  called  total  reflection  within  the  stone. 
The  effect  of  this  is  to  light  the  stone's  interior.  Moreover,  the  rays 
of  light  are  concentrated  on  a  smaller  part  of  the  surface  than  is  the 
case  with  less  highly  refracting  minerals,  and  thus  also  internal  illumi- 
nation is  produced.  The  most  important  result  of  the  high  refractive 
power  of  the  diamond  is  the  wide  dispersion  of  the  spectrum,  causing 
the  red  rays  to  be  widely  separated  from  the  blue  rays,  and  strong 
lights  of  one  color  to  be  transmitted  to  the  eye,  as  could  not  be  the 
case  were  the  different  rays  less  widely  separated.  It  is  this  power 
of  flashing  different  colored  lights  which  gives  the  diamond  one  of  its 
chief  charms.  The  index  of  refraction  ranges  from  2.40  for  the  red 
rays  to  2.46  for  the  violet  rays.  Ordinary  glass  has  an  index  of  refrac- 
tion for  the  red  rays  of  only  1.52,  and  for  the  violet  1.54,  making  the 
spectrum  only  about  half  as  long  as  that  produced  by  the  diamond. 

Another  pleasing  property  of  the  diamond  is  the  fact  that  it  is 
usually  more  brilliant  by  artificial  light  than  by  natural,  although  some 
individual  stones  have  a  reverse  behavior. 

Diamond  is  much  the  hardest  substance  known  in  nature,  and  as 


the  proverb  says,  only  the  diamond  is  able  to  "  cut  diamond."  It  is 
ranked  10  in  the  scale  of  hardness,  corundum  being  the  next  below 
it.  It  is  really  separated  by  a  wide  gap  from  the  latter  mineral, 
however,  and  its  hardness  is  as  much  greater  than  that  of  corundum 
as  that  of  corundum  is  greater  than  that  of  the  first  mineral  in 
the  scale.  This  hardness  of  diamond  affords  a  ready  means  of 
identifying  it,  as  it  will  scratch  all  other  substances.  It  is  popularly 
supposed  that  diamond  is  the  only  mineral  which  will  scratch 
glass  to  any  extent,  and  a  stone  found  is  often  reported  to  be 
diamond  because  it  will  do  this.  As  a  matter  of  fact,  however, 
all  quartz  will  scratch  glass,  and  the  harder  minerals,  garnet, 
topaz,  beryl,  and  others  will  do  so  easily.  Minerals  which  will  scratch 
glass  are,  therefore,  common.  The  diamond  cuts  glass  instead  of  scratch- 
ing it,  and  is  the  only  mineral  that  will  do  this.  Although  the  diamond 
is  so  hard,  it  is  not  tough,  and  can  be  easily  broken  with  the  blow 
of  a  hammer.  It  was  a  tradition  of  the  ancients  that  if  a  diamond 
were  put  upon  an  anvil  and  struck  with  a  hammer,  both  hammer  and 
anvil  would  be  shattered  without  injuring  the  diamond  in  the  least. 
One  occasionally  hears  this  statement  made  even  at  the  present  day. 
It  is  entirely  untrue,  however,  the  diamond  being  as  brittle  as  at  least 
the  average  of  crystallized  minerals. 

The  specific  gravity  of  the  diamond  is  about  three  and  one-half  times 
that  of  water,  determinations  showing  variations  between  3.49  and  3.53. 
Carbonado  is  lower,  ranging  between  3.14  and  3.41.  Diamond  is  thus 
a  comparatively  heavy  mineral,  the  only  ones  among  the  gems  which 
much  exceed  it  in  specific  weight  being  hyacinth,  garnet,  ruby, 
sapphire,  and  chrysoberyl. 

Diamond  becomes  strongly  electric  on  friction,  so  that  it  will  pick 
up  pieces  of  paper  and  other  light  substances.  It  does  not  retain  its 
electricity  long,  however,  usually  not  over  half  an  hour.  It  is  not 
a  conductor  of  electricity,  differing  in  this  respect  from  graphite, 
which  is  a  good  conductor.  Diamond  becomes  phosphorescent  on  rub- 
bing with  a  cloth,  giving  out  a  light  which  is  visible  in  the  dark. 
Some  stones,  as  if  they  took  up  light  from  the  sun  and  gave  it  out 
again,  emit  a  phosphorescent  light  after  being  exposed  to  the  sun's 
rays  for  a  time.  This  has  often  been  stated  to  be  a  property  of  all 
diamonds,  but  this  is  not  true,  only  certain  stones  exhibiting  it.  As 
first  suggested  by  Kunz,  it  is  probable  that  this  phosphorescence  is 
due  to  minute  quantities  of  hydrocarbons  which  are  heated  by  the 
friction  given  the  stone.  It  is  curious  to  note  that  the  light 
is  in  some  cases  given  out  only  from  certain  crystal  faces.  Thus 

70 


KAJPOOTANA 


SAIDARABAD 

Crolcorisdct0 


Madra 

MYSORE 


Map  of  India,  showing  diamond  fields.    After  Boutan 


diamonds  are  known  which  give  out  light  from  the  cubic  faces  but 
not  from  the  octahedral,  while  others  are  reported  as  giving  out  light 
of  different  colors  from  different  faces. 

''The  name  diamond  comes  from  the  Greek  adamas,  which  means 
unconquerable.  This  term  was  doubtless  applied  because  of  the  great 
resistant  power  assigned  to  the  mineral  by  the  ancients.  Besides  the 
well-known  tradition  that  it  could  not  be  broken  by  hammer  and  anvil, 
they  believed  that  the  diamond  could  be  subdued  or  broken  down  only 
when  dipped  in  warm  goat's  blood.  Our  words  adamant  and  adamantine 
are  also  derived  from  adamas,  the  latter  term  still  being  used  to  describe 
the  luster  of  the  diamond.  The  change  of  adamas  into  the  word  diamond 
is  thought  by  some  to  have  come  from  prefixing  to  it  the  Italian  diafano, 
transparent,  in  allusion  to  its  possessing  the  property  of  transparency. 

According  to  classical  mythology  the  diamond  was  first  formed  by 
Jupiter,  who  turned  into  stone  a  man  known  as  Diamond  of  Crete, 
for  refusing  to  forget  him  after  he  had  ordered  all  men  to  do  so. 
Many  medicinal  virtues  were  ascribed  to  the  diamond,  it  being  regarded 
as  an  antidote  for  poisons  and  a  preventive  of  mania. 

The  world's  supply  of  diamonds  has  come  almost  wholly  from  three 
countries  —  India,  Brazil,  and  South  Africa.  Up  to  the  beginning  of  the 
eighteenth  century  India  was  the  only  source  of  diamonds  known.  The 
diamond  fields  of  India  occur  chiefly  in  the  eastern  and  southern  por- 
tions of  the  peninsula.  The  famed  region  of  Golconda  is  in  the  southern 
part.  This  is  the  territory  whence  have  come  the  most  celebrated  Indian 
stones,  such  as  the  Kohinoor  and  the  Hope  Blue.  The  French  traveler 
Tavernier  reported  when  he  was  there  in  1665,  that  sixty  thousand 
men  were  then  employed  in  these  mines.  Now  the  mines  have  all 
been  given  up  and  the  region  is  abandoned. 

The  present  yield  of  Indian  diamonds  comes  almost  wholly  from 
mines  in  a  district  south  of  Allahabad  and  Benares.  The  diamonds 
occur  here,  as  universally  in  India,  in  a  conglomerate  or  sandstone 
made  up  of  the  remains  of  older  rocks. 

The  mines  are  worked  almost  wholly  by  natives  of  the  lower  caste, 
attempts  of  Europeans  to  conduct  the  mining  not  having  met  with 
success.  The  natives  separate  the  diamonds  by  washing,  or  where  the 
rock  is  too  hard  for  such  methods,  break  it  up  by  heating  and  throw- 
ing cold  water  upon  it.  The  production  of  diamonds  from  all  of  India 
is  at  the  present  time  very  small,  not  reaching  a  million  dollars  a  year 
in  value.  It  is  likely  in  time  to  disappear  altogether,  since  most  of  the 
old  mines  have  been  abandoned,  and  even  their  location  forgotten, 
and  the  returns  from  the  present  mines  are  not  very  profitable. 

71 


Most  of  the  famous  large  diamonds  of  the  world  have  come  from 
India,  their  origin  being  usually  traceable  to  a  period  between  the 
thirteenth  and  eighteenth  centuries.  Some  of  the  best  known  of  these 
are  the  Kohinoor,  Pitt,  Orloff,  Great  Mogul,  Florentine,  and  Sancy. 

The  Kohinoor  first  appeared  in  history  in  the  year  1304.  It  was 
at  that  time  mentioned  as  acquired  by  the  Sultan  Alaeddin  from  the 
Kajah  of  Malwa,  in  whose  family  it  had  long  been  held  as  an  heir- 
loom. It  was  later  restored  to  the  Rajah  of  Gwalior;  but  on  the 
defeat  of  this  official,  in  1526,  by  Humairen,  emperor  of  Hindostan,  the 
stone  was  presented  to  the  latter  by  some  of  the  former's  adherents.  Sul- 
tan Baber  states  that  at  this  time  the  diamond  was  valued  at  "  half  the 
daily  expense  of  the  whole  world."  The  stone  remained  in  the  posses- 
sion of  the  Mogul  dynasty  until  the  invasion  of  India  in  1739  by 
Nadir  Shah,  the  Persian  conqueror.  The  reputed  exclamation  of  the 
latter  when  he  first  saw  the  stone,  "Koh-i-Nur!"  ("Mountain  of 
Light!")  gave  it  the  name  by  which  it  has  since  been  known. 
As  the  reward  of  an  alliance  the  diamond  was  given  by  the  son 
of  Nadir  to  Ahmed  Shah,  founder  of  the  Durain  Afghan  empire,  in 
1751.  A  successor  of  the  latter  sought  to  conceal  the  stone  from 
a  usurper  by  embedding  it  in  the  plaster  of  his  cell,  but  after  lying 
hidden  in  this  way  for  many  years  it  became  exposed  and  was  once 
more  restored  to  the  Afghan  crown.  An  Indian  prince,  Runjit  Singh, 
later  obtained  the  diamond  by  conquest  and  brought  it  to  Lahore 
where  it  remained  until  English  rule  was  established.  In  1850  it  was 
sent  to  England  in  charge  of  two  officers.  It  weighed  at  that  time 
186TY  carats.  It  had  not  a  symmetrical  shape,  its  cutting  being  con- 
fined, after  the  usual  manner  of  Indian  lapidaries,  to  fashioning  rude 
facets  on  the  surface.  It  also  contained  two  or  three  flaws.  In  order 
to  remove  these,  and  give  it  a  symmetrical  shape,  the  stone  was  cut 
in  London,  in  1852,  by  Messrs.  Coster,  of  Amsterdam,  to  the  form 
of  a  brilliant.  About  80  carats  were  sacrificed  in  this  process,  and 
the  stone  at  present  has  a  weight  of  106  carats.  The  quality  of  the 
Kohinoor  is  not  the  finest,  it  having  a  slight  grayish  tinge;  but  on 
account  of  its  romantic  history  it  is  one  of  the  most  famous,  if  not 
the  most  famous,  of  diamonds. 

The  diamond  known  as  the  "Regent"  or  "Pitt"  was  found  in 
India  in  1701  by  a  slave,  who  to  conceal  it,  cut  his  leg  that  he 
might  put  it  in  the  bandage  thus  made  necessary.  He  thus  escaped 
with  it  to  the  coast,  and  offered  the  stone  to  an  English  skipper  as 
payment  for  passage  to  a  free  country.  The  latter  on  receiving  the 
diamond  threw  the  slave  into  the  sea.  He  then  sold  the  gem  to  a  dia- 

72 


mond  merchant  for  five  thousand  dollars,  squandered  the  money  in 
dissipation,  and  went  and  hanged  himself.  The  diamond  was  sold  by 
the  merchant  to  Sir  Thomas  Pitt,  Governor  of  Fort  St.  George  at 
Madras,  for  one  hundred  and  twenty  thousand  dollars.  When  the 
latter  reached  England  he  found  numerous  stories  afloat  to  the  effect 
that  he  had  obtained  the  gem  by  foul  means.  These  reports  caused 
him  great  distress,  both  because  of  their  imputation  of  dishonesty  and 
because  of  making  widely  known  his  possession  of  such  a  treasure. 
He  developed  a  morbid  fear  that  he  would  lose  or  be  robbed  of  the 
gem,  and  while  he  possessed  it  is  said  never  to  have  slept  two  nights 
under  the  same  roof,  and  to  have  gone  about  much  in  disguise.  During 
the  stay  of  the  stone  in  London  it  was  cut  into  the  form  of  a  brilliant, 
the  cutting  reducing  its  weight  from  410  to  136f  carats.  In  1717  it 
was  sold  to  the  Regent  of  France,  Duke  of  Orleans,  for  about  six  hun- 
dred and  seventy-five  thousand  dollars,  which,  together  with  what  was 
received  for  the  dust  obtained  in  the  cutting,  made  a  profit  to  Pitt 
of  at  least  five  hundred  thousand  dollars.  The  diamond  remained 
among  the  French  crown  jewels  till  1792,  when  it  was  stolen,  in  com- 
pany with  many  other  precious  stones,  from  the  Garde  Meuble.  Shortly 
after  a  note  was  received,  evidently  from  the  robbers,  saying  that  the 
diamond  would  be  found  in  the  Alice  des  Veuves.  In  this  way  the 
diamond  was  recovered,  and  it  has  remained  in  the  French  treasury 
since.  It  was  at  one  time  pledged  by  Napoleon  to  the  Dutch  govern- 
ment as  a  means  of  securing  a  loan  of  two  and  a  half  millions  of 
dollars;  but  aside  from  this,  its  later  history  seems  to  have  been 
uneventful.  It  is  exhibited  at  present  in  the  Galerie  Apollon  in  the 
Louvre  in  Paris.  It  is  one  of  the  purest  and  finest  of  large  diamonds. 
Its  present  dimensions  are :  Length,  one  and  one-sixth  inches ;  breadth, 
one  inch;  and  thickness,  three  quarters  of  an  inch. 

The  Orloff  diamond  is  to  the  Russian  crown  what  the  Kohinoor 
is  to  the  British.  Our  first  knowledge  of  this  stone  is  of  its  forming 
one  of  the  eyes  of  a  Hindoo  idol.  How  long  it  had  glittered  there 
is  not  known ;  but  its  existence  came  to  the  ears  of  a  French  grenadier 
some  time  in  the  eighteenth  century.  This  individual  resolved  to  gain 
possession  of  the  diamond  by  pretending  to  become  a  worshiper  of  the 
idol,  and  so  gained  the  confidence  of  the  Hindoo  devotees  that  they 
appointed  him  special  guardian  of  the  god.  He  shortly  improved 
the  opportunity  on  a  dark  and  stormy  night  to  tear  out  the  adaman- 
tine eye  and  escape  with  it  to  Madras.  There  he  sold  it  to  an 
English  sea  captain  for  ten  thousand  dollars  and  the  latter  to  a  Jew 
for  sixty  thousand  dollars.  The  Jew  merchant  some  time  after  brought 

73 


the  stone  to  Amsterdam,  where  it  was  seen  by  Prince  Orloff,  of  Russia, 
and  purchased  for  the  sum  of  four  hundred  and  fifty  thousand  dollars 
in  cash  and  an  annuity  of  twenty  thousand  dollars.  By  Orloff  the 
diamond  was  presented  to  Catherine  II.  of  Russia,  the  Czarina,  as 
a  means  of  restoring  him  to  her  favor,  he  having  forfeited  this  some 
time  before.  Catherine  accepted  the  gift,  and  the  diamond  has  remained 
among  the  Russian  crown  jewels  since.  It  is  mounted  in  the  Imperial 
scepter,  and  is  hence  sometimes  known  as  the  " Scepter"  diamond. 
It  is  the  largest  of  the  Indian  diamonds  now  extant,  its  weight  being 
193  carats.  It  has  the  shape  and  about  the  size  of  half  a  pigeon's 
egg  with  facets.  On  one  surface  is  a  V-shaped  incision,  and  the  stone 
has  a  slight  yellow  tinge. 

Our  knowledge  of  the  diamond  called  the  "  Great  Mogul "  is  wholly 
of  the  past.  It  was  described  by  the  French  traveler  Tavernier,  as  seen 
by  him  in  1665  at  the  court  of  Aurung-zeb,  a  ruler  of  Hindostan. 
Tavernier  gave  its  weight  at  the  time  he  saw  it  as  319^  ratis, 
i.e.,  280  carats;  but  states  that  it  had  been  cut  from  a  stone  which 
weighed  in  the  rough  787|-  carats.  The  diamond  is  further  described 
by  him  as  having  the  form  (though  not  the  size,  as  often  stated) 
of  an  egg  cut  in  half,  as  being  rose  cut,  round,  and  very  high  on  one 
side,  and  as  being  of  a  very  pure  water.  The  subsequent  history 
of  the  diamond  is  not  known.  Attempts  have  been  made  to  identify 
it  with  the  Kohinoor  and  Orloff;  but  in  the  view  of  Streeter,  the  emi- 
nent English  .authority  on  diamonds,  there  is  no  ground  for  these 
views.  The  "Great  Mogul"  has  probably  been  either  wholly  lost, 
or  it  has  been  cut  into  smaller  stones. 

The  "Florentine"  diamond  is  also  known  as  the  "Austrian  Yellow" 
and  "Tuscan."  It  has  a  weight  of  139^  carats,  and  is  cut  so  as  to  form 
a  nine-rayed  star  of  the  rose  form.  It  is  of  a  citron  hue.  Its  authentic 
history  is  known  only  back  to  the  time  of  Tavernier,  that  writer  having 
seen  it  in  the  collection  of  the  Grand  Duke  of  Tuscany.  By  the  latter 
it  was  transferred  to  the  Empress  Maria  Theresa,  and  it  has  since 
remained  in  the  possession  of  the  royal  House  of  Austria.  It  is  often 
asserted  to  have  been  owned  by  Charles  the  Bold,  and  to  have  been 
lost  by  him  on  the  battle-field  of  Nancy  or  Granson;  but  Streeter 
regards  this  story  incorrect. 

/<  The  Sancy  diamond  was  purchased  in  1570  in  Constantinople  by 
M.  de  Sancy,  French  ambassador  to  the  Ottoman  court.  On  his  return 
to  France  he  permitted  his  sovereign,  Henry  IV.  of  Navarre,  to  use 
it  as  security  for  a  loan,  for  the  purpose  of  employing  &  body  of  Swiss 
recruits.  But  the  messenger  to  whom  the  gem  was  intrusted  disap- 

74 


peared  on  the  way  to  accomplish  his  errand,  and  after  some  time  it 
was  learned  that  he  had  been  assassinated.  Confident,  however,  that 
he  had  found  some  way  of  guarding  the  gem,  de  Sancy  had  the  body 
of  the  messenger  disinterred,'  and  in  his  stomach  the  diamond  was  found.  " 

Some  time  after  de  Sancy  sold  the  diamond  to  Queen  Elizabeth 
of  England,  and  it  remained  in  the  possession  of  the  English  royal 
family  until  about  1695,  when  it  was  sold  to  Louis  XIV.  of  France, 
for  one  hundred  and  twenty-five  thousand  dollars.  It  was  stolen  in 
the  robbery  of  the  Garde  Meuble,  but  turned  up  about  1828,  and  was 
sold  by  a  French  merchant  to  Prince  Demidoff.  It  then  went  back 
to  the  land  of  its  birth,  India,  for  it  was  bought  by  an  Indian  prince, 
in  whose  possession  it  either  remains,  or,  according  to  some  authorities,  it 
is  owned  by  a  French  syndicate.  The  Sancy  is  almond-shaped,  facetted 
on  both  sides,  and  weighs  53^  carats. 

After  those  of  India  the  Brazilian  diamond-fields  were  the  first 
important  ones  to  become  known.  The  date  of  their  discovery  is  gen- 
erally considered  to  be  1729.  The  diamonds  were  first  found  in  river 
sands  which  had  for  some  time  been  worked  for  gold  by  adventurers 
who  penetrated  into  the  region  from  the  coast,  but  who  attached  no 
importance  to  the  little  bright  crystals  sometimes  seen  in  the  bottoms 
of  their  gold  pans.  It  is  said  that  a  monk  who  had  seen  diamonds 
mined  in  India  was  the  first  to  recognize  the  nature  of  the  Brazil- 
ian stones.  The  news  of  the  discovery  reached  the  Portuguese  gov- 
ernment, and  the  king  of  Portugal  immediately  took  possession  of 
all  lands  likely  to  be  diamondiferous,  at  the  same  time  inaugurating 
a  despotic  rule  which  burdened  the  country  for  many  years.  The  dia- 
monds at  first  obtained  came  wholly  from  the  sands  and  gravels  of  the 
brook  and  river  beds.  These  sands,  universally  known  by  the  Portu- 
guese word  cascalhos,  still  afford  a  large  part  of  the  supply  of  Brazilian 
diamonds.  Extensive  upland  deposits  are,  however,  now  also  known. 
These  are  called  servicos  do  campo,  while  the  river  deposits  are  known 
as  servicos  do  rio.  Several  provinces  of  Brazil  afford  diamonds,  vi/,., 
Bahia,  Goyaz,  Matto  Grosso,  Parana,  and  Minas  Geraes.  In  all  these, 
except  the  first  and  last  named,  the  mining  is  desultory,  and  consists 
simply  in  washing  river  sands  by  means  of  wooden  bowls.  Enough  dia- 
monds are  thus  obtained  to  afford  a  precarious  living  to  the  fiscadores, 
as  they  are  called,  who  follow  this  occupation.  The  chief  diamond- 
bearing  region  is  in  the  province  of  Minas  Geraes,  and  the  city  of  Dia- 
mantina  is  its  geographical  and  commercial  center.  This  city  is  located 
about  five  hundred  miles  from  the  sea  coast,  at  the  head  waters  of  the 
Rio  Jequitinhonha  and  Rio  Doce.  The  valleys  of  these  rivers  are 

75 


especially  rich  in  diamonds,  and  form  the  region  which  has  been 
longest  and  most  successfully  worked.  Here  "wet  diggings"  are  car- 
ried on  in  the  beds  of  streams,  laid  bare  by  conducting  the  waters  into 


Map  of  principal  diamond-fields  of  Brazil.    After  Boutan 

new  channels  by  means  of  flames.  The  work  can  only  be  carried  on 
in  the  dry  season,  as  in  the  wet  season  the  quantity  of  water  in  the 
rivers  makes  them  ungovernable,  and  sometimes  even  in  the  dry  season 
it  happens  that  a  miner  has  barely  got  the  artificial  way  constructed 

76 


iKJE 


before  the  waters,  increased  in  volume,  suddenly  destroy  it.  The  fall  of 
water  from  the  artificial  sluice  is  often  employed  to  turn  a  wheel  to 
keep  the  old  channel  pumped  dry,  but  little  use  is  made  of  this  power 
for  other  purposes.  When  the  river  bed  has  thus  been  laid  bare,  search 
is  made  with  a  long  iron  rod  for  huge  pot-holes,  known  as  caldeiros, 
which  experience  has  shown  are  more  likely  to  contain  quantities  of 
diamonds  than  the  ordinary  river  bed.  This  is  natural,  since  the 
diamonds  resist  longer  than  other  stones  the  constant  wear  due  to  the 
whirling  about  of  the  water  in  the  pot-holes  and  hence  gather  there. 
It  is  said  that  sometimes  on  removal  of  a  little  sand  large  aggrega- 
tions of  pure  diamonds  are  to  be  seen.  A  single  small  pot-hole  is 
said  to  have  yielded  8,000  carats,  or  about  6  pounds  of  diamonds. 
The  caldeiros  have  now  been  nearly  all  dug  over,  however,  and  the 
finding  of  a  new  one  is  rare.  The  separation  of  the  diamonds  from 
the  accompanying  sand  and  gravel  is  usually  performed  by  washing, 
in  the  manner  thus  described  by  Gorceix:* 

"  The  sands  are  placed,"  he  says,  "  in  portions  of  two  hundred 
to  two  hundred  and  fifty  pounds,  in  a  kind  of  hod  or  rectangular 
trough,  only  three  sides  of  which  are  inclosed.  The  hods  are  arranged 
by  twos,  fours,  or  sixes  by  the  side  of  a  trough  of  water  about  a  foot 
and  a  half  deep  so  that  their  bottoms  shall  be  slightly  inclined  toward 
it.  A  workman  standing  in  the  trough  before  each  hod  dashes  water 
upon  the  sand  in  it.  The  clay  and  the  very  fine  sands  are  carried 
away  and  the  first  separation  is  made.  The  larger  pieces  remaining 
in  the  top  of  the  sand  are  picked  away.  The  diamond  is  to  be  found 
in  the  two  upper  thirds  of  the  mass  that  is  left,  the  lower  part  being 
nearly  sterile.  The  washing  is  afterward  finished  in  bowls  a  little 
deeper  and  a  little  more  conical  than  those  used  by  the  gold-washers. 
The  washer  puts  the  sand  in  the  bowl  and  fills  it  with  water;  then  by 
whirling  the  bowl  and  shaking  it  up  and  down  while  the  sand  is  float- 
ing around  in  it,  and  being  careful  to  stir  it  from  time  to  time  with 
his  hand,  he  determines  a  classification  in  the  order  of  density.  This 
work  would  be  easy  if  he  were  washing  gold,  for  that  metal  is  heavier 
than  the  substances  with  which  it  occurs,  and  always  goes  to  the  bot- 
tom. The  diamond,  however,  having  a  density  only  about  three  and 
a  half  times  greater  than  that  of  water,  not  much  more  than  that 
of  quartz  and  tourmaline,  and  less  than  that  of  the  oxides  of  iron 
and  titanium,  its  constant  companions,  settles  in  the  middle  layers. 
The  washer,  after  several  rinsings,  removes  the  upper  particles,  hardly 
looking  at  them;  and  when  he  has  reached  a  certain  level,  which  his 

*  Popular  Science  Monthly,  Vol.  XXI.,  p.  616. 

77 


Preliminary  concentration  of  diamond-bearing  gravel  by  dashing  water  upon  it  from 
broad  wooden  bowls  known  as  bateas.    Near  Diamantina,  Brazil 


Searching  washed  gravel  for  diamonds.    Near  Diamantina,  Brazil 

78 


skill  recognizes  at  once,  tips  his  bowl  slightly  so  as  to  let  the  water 
run  off  in  a  thin  film,  and  perceiving  the  glittering  crystals  of  the 
diamond  picks  them  out  with  his  fingers.  The  vigilance  of  the  over- 
seers must  be  redoubled  at  this  stage,  particularly  when  slaves  are 
employed,  for  I  know  of  nothing  equal  to  the  skill  of  the  slaves  in 
finding  diamonds,  except  that  with  which  they  make  them  disappear 
if  the  vigilance  of  the  superintendent  is  relaxed  for  an  instant.  I  can- 
not describe  all  the  artifices  employed;  but  I  should  remark  that  since 


Agua  Suja,  Brazil,  showing  soil  worked  for  diamonds.     An  example  of  dry  diggings 

the  works  have  become  free,  fraud  has  greatly  diminished.    Under  the 
old  rule  it  overtook  half  the  diamonds  in  the  gravels." 

This  method  of  washing  is  not  confined  to  the  river  sands,  but 
is  also  used  to  separate  the  diamonds  in  the  upland  deposits.  These 
upland  deposits  include  strata  of  considerable  extent,  composed  of  clay 
derived  from  the  decomposition  of  a  coarse  conglomerate.  The  strata 
are  divisible  into  three  distinct  layers.  The  first,  a  soil  cap,  is  some- 
what diamondiferous ;  the  next  low^er,  a  clay  called  secundina,  is  regarded 
sterile,  probably  on  account  of  its  tenacity,  which  makes  it  almost  unwash- 
able ;  while  the  third,  called  taua,  is  the  diamond  layer  par  excellence. 
Large  areas  of  this  sort  have  been  and  are  still  being  worked  with 
more  or  less  profitable  returns,  an  illustration  of  the  latter  being  given 
by  Gorceix,  who  states  that  he  knows  of  miners  who  have  washed 
the  cascalhos  of  Bagagem  for  twenty  years  without  finding  a  single 
diamond  of  value. 

79 


The  origin  of  the  Brazilian  diamonds  is  not  well  understood.  They 
do  not  appear  to  have  originated,  like  those  of  South  Africa,  in  eruptive 
rocks,  as  there  are  little  or  no  traces  of  such  rocks  now  to  be  seen. 
They  were  formerly  supposed  to  be  constituents  of  a  quartz  schist, 
called  itacolumite,  from  Itacolumi,  a  prominent  mountain  peak  near 
Diamantina,  but  this  is  not  now  believed  to  be  the  case.  The  present 
Director  of  the  Geological  Commission  of  Brazil,  Orville  A.  Derby, 
is  of  the  opinion  that  the  diamonds  may  have  been  formed  out  of  the 
carbon  contained  in  the  phyllites  (clay  schists)  of  the  region  by  the 
intrusion  in  them  of  pegmatite  veins. 

The  quantity  of  diamonds  now  obtained  from  Brazil  is  compara- 
tively small,  the  total  production  in  1880  being  only  about  forty  pounds 
(80,000  carats).  During  the  past  few  years  an  extensive  drought  has 
prevailed  in  the  diamond-bearing  regions,  which  has  favored  search 
for  the  stones  and  increased  the  output.  It  is  difficult  at  any  time, 
however,  to  learn  the  exact  production,  since  there  is  much  smug- 
gling, owing  to  the  high  duty  of  sixteen  per  cent  levied  on  exported 
diamonds. 

The  largest  diamond  from  Brazil  that  is  now  known  is  that  called 
"Star  of  the  South,"  which  weighed  in  the  rough  254.5  carats,  and 
after  being  cut,  125  carats.  This  was  found  in  1853  by  a  negro  slave 
woman.  It  was  a  dodecahedron,  and  has  a  peculiarity  that  no  other 
diamond  possesses,  in  giving  off  in  certain  lights  a  rose  tint,  although 
perfectly  white  itself.  It  was  sold  for  one  hundred  and  seventy-five 
thousand  dollars  to  a  Paris  syndicate,  which  is  said  in  turn  to  have 
sold  it  to  an  Indian  prince. 

The  next  great  deposit  of  diamonds  to  be  found  after  that  of  Brazil, 
and  by  far  the  most  important  known  to-day,  is  that  of  South  Africa. 

The  first  discovery  of  diamonds  here  is  to  be  credited,  as  has  so  often 
been  true  in  the  finding  of  gems,  to  the  picking  up  of  pretty  stones 
by  children.  Among  such  pebbles  gathered  by  a  child  of  Daniel  Jacobs, 
a  Boer  farmer  living  near  the  present  town  of  Barkly  West  on  the 
Vaal  River,  one  was  thought  by  John  O'Reilly,  a  roving  trader,  to  be 
a  diamond.  To  test  the  matter  he  sent  the  stone  to  Dr.  Atherstone, 
a  mineralogist  at  Grahamstown,  who  at  once  identified  it  as  a  veritable 
diamond,  and  expressed  the  belief  that  more  were  likely  to  be  found 
in  the  region.  This  find  was  made  in  1867,  but  no  more  diamonds 
were  discovered  until  March,  1869,  when  a  superb  stone  weighing 
S3£  carats,  and  which  not  long  after  brought  a  price  of  one  hundred 
and  twenty-five  thousand  dollars,  was  picked  up  in  the  same  region. 
This  discovery  was  sufficient  to  set  a  tide  of  diamond-seekers  toward 

80 


I 


a 
w 


the  valley,  and  soon  their  camps  were  spread  all  up  and  down  the 
Vaal  River.  The  separation  of  the  diamonds  from  the  gravel  was 
at  first  performed  by  hand  panning,  after  the  method  of  the  Brazilian 
and  Indian  miners;  but  after  a  time  a  piece  of  apparatus  consisting 
of  a  long  box  with  a  sieve  bottom,  mounted  so  that  it  could  be  swung 
back  and  forth,  came  into  use.  This  was  called  sometimes  a  "baby" 
and  sometimes  a  "cradle."  The  meshes  of  the  sieve  were  of  such 
size  as  to  allow  the  fine  refuse  to  pass  through,  while  the  medium- 
sized  pebbles  likely  to  contain  diamonds  were  retained  and  rolled  into 
a  tub.  The  contents  of  the  latter  after  shaking  were  turned  upon 
a  "sorting  table"  and  the  diamonds  picked  out  by  careful  scraping. 
By  use  of  this  apparatus  a  larger  quantity  of  the  gravel  could  be 
shaken  at  a  time  with  less  labor.  In  this  way  large  areas  of  the 
gravel  beds  of  the  valley  were  sorted  over  for  diamonds.  It  soon 
appeared,  however,  that  though  the  extent  of  the  diamond  -  bearing 
gravels  was  great  in  area  it  was  small  in  depth,  and  though  large 
numbers  of  men  found  profitable  employment  there  for  a  time,  if  no 
other  source  of  supply  had  appeared  diamond-mining  in  South  Africa 
would  probably  long  ago  have  been  a  thing  of  the  past.  But  in 
August,  1870,  a  farm  overseer  by  the  name  of  De  Klerk,  living  at  Ja- 
gersfontein,  having  learned  that  diamonds  were  usually  accompanied 
in  the  river  diggings  by  garnets,  and  having  found  some  of  the  latter 
on  his  farm,  went  to  work  with  a  common  wire  sieve,  and  at  a  depth 
of  six  feet  found  a  fine  diamond  of  50  carats.  A  month  later  a  similar 
discovery  was  made  at  the  place  now  called  Kimberley,  and  further 
and  deeper  digging  only  disclosed  more  and  more  of  the  diamonds. 
The  news  of  these  discoveries  spread  rapidly,  and  soon  the  farms  on 
which  the  diamonds  had  been  found  were  staked  out  in  claims  by 
hordes  of  diamond  diggers.  The  returns  from  the  diggings  proved 
profitable ;  but  the  diamond-bearing  areas  were  so  small  that  the  intri- 
cacy of  the  claims  within  them  became  a  serious  matter.  At  first  roads 
were  left  by  common  consent  between  the  claims  to  provide  means 
of  transportation  and  places  for  work,  as  shown  in  the  accompanying 
view  of  the  Kimberley  mines  in  1872.;  but  as  the  roads  were  too  full 
of  diamonds  to  be  spared,  they  were  in  time  cut  away,  and  the  plan 
was  adopted  of  removing  the  diamond-bearing  earth  by  means  of  cars 
carried  by  long  wire  ropes  to  the  surface.  Each  claim  or  owner  had 
his  own  system  of  pulleys,  and  the  mines  soon  came  to  look  as  if  covered 
by  a  vast  spider's  web.  In  ]  885,  within  an  area  of  seventy  acres,  at  Kim- 
berley forty-two  companies  and  fifty-six  private  firms  or  individuals 
were  working.  As  the  diggings  grew  deeper  the  situation  became 

81 


more  and  more  serious  because  of  the  different  depths  to  which  differ- 
ent claims  were  carried.  The  walls  of  the  outlying  areas  disintegrated 
rapidly,  and  fell  from  time  to  time  in  great  masses,  causing  sad  loss 
of  life.  Moreover,  the  immense  output  of  diamonds,  and  extensive 
competition  between  the  different  producers,  caused  a  lowering  of  the 
price  which  made  it  unprofitable  to  work  many  of  the  poorer  parts 
of  the  mines.  A  consolidation  of  interests  seemed  the  only  way  out 
of  these  difficulties,  and  this  was  finally  accomplished  under  the  leader- 
ship of  Cecil  Rhodes.  In  1888  a  joint  stock  company,  known  as  the 
De  Beers  Consolidated  Mines,  Limited,  was  formed  to  operate  the  impor- 
tant diamond  properties  in  the  region  of  Kimberley.  The  workings 
of  this  company  have  proved  highly  satisfactory,  both  in  promoting 
a  safe  and  economical  extraction  of  the  diamonds  and  in  limiting 
their  output.  Under  the  new  management  the  system  of  open-cut 
workings  has  been  abandoned  in  all  the  mines  except  the  Premier, 
and  the  diamond  -  bearing  ground  is  mined  by  a  system  of  tunnels 
at  various  levels.  From  these  it  is  hoisted  to  the  surface  through 
shafts,  and  then  spread  out  over  large  areas,  called  floors,  to  disinte- 
grate. The  disintegration  is  accomplished  by  exposure  to  sun  and 
rain,  huge  harrows  being  drawn  frequently  over  the  floors  to  assist 
in  the  work.  The  time  required  for  proper  disintegration  varies  from 
three  to  six  months  according  to  the  nature  of  the  rock.  When  suffi- 
ciently disintegrated,  the  rock  is  carried  to  machines  which  wash  away 
the  finer  particles  and  mechanically  concentrate  that  of  a  size  likely 
to  contain  diamonds  of  value. 

For  a  long  time  the  diamonds  were  picked  out  from  this  concen- 
trate by  hand,  the  assortment  of  pebbles  being  spread  on  tables  and 
picked  over.  It  has  lately  been  found,  however,  as  already  noted, 
that  by  running  the  concentrate  over  percussion  tables  the  surfaces 
of  which  are  covered  with  a  thick  coat  of  grease,  that  the  diamonds 
are  caught  and  held  by  the  grease  while  the  valueless  minerals  pass  on. 
In  this  way  a  more  nearly  complete  as  well  as  more  rapid  extrac- 
tion of  the  diamonds  is  secured  than  when  the  concentrate  is  sorted 
by  hand. 

After  being  sorted  out  the  diamonds  are  cleaned  by  boiling  in  a  mix- 
ture of  nitric  and  sulphuric  acids,  rinsing  in  water,  and  finally  washing 
in  alcohol.  They  are  then  assorted  according  to  quality  into  about  ten 
classes,  ranging  from  the  finest,  called  ll  close  goods,"  to  the  poorest, 
called  "  boart."  The  diamonds  belonging  to  the  first  eight  of  these 
classes  are  then  again  assorted  according  to  color,  the  "  blue  whites  " 
standing  first  and  the  "yellows"  last.  They  are  then  wrapped  in 

82 


parcels  and  forwarded  to  London,  where  they  are  reasserted  and  sup- 
plied to  the  trade.  The  color,  size,  and  quality  of  the  diamonds  from 
the  different  mines  vary  considerably,  but  are  fairly  constant  for  each 
mine.  A  majority  of  the  diamonds  from  the  De  Beers  mine,  for  instance, 
are  "yellows,"  colorless  stones  being  almost  never  found  there.  The 
Dutoitspan  mine,  on  the  other  hand,  produces  many  blue-white  and 
white  stones,  and  these  are  generally  of  large  size.  The  iiamonds 

o  */  o 

of  the  Jagersfontein  mine  excel  all  others  in  quality,  superb  blue-white 
stones  being  the  rule. 

From  the  South  African  mines  have  been  obtained  the  world's 
largest  diamonds,  unless  the  mythical  "Grand  Mogul"  and  question- 
able "  Braganza "  are  to  be  excepted.  The  largest  and  finest  of1  the 
South  African  stones,  also  the  superior  of  any  other  known  diamond, 
is  that  called  the  "Jubilee"  or  "  Excelsior."  This  stone  weighs  239 
carats,  and  was  cut  from  a  crystal  of  9 7 If  carats  found  at  Jagers- 
fontein in  1893.  It  is  cut  as  a  brilliant,  and  has  the  following  dimen- 
sions: Length,  If  inch;  breadth,  If  inch;  depth,  1  inch. 

Other  noted  South  African  diamonds  are  the  "Tiffany,"  a  yellow 
diamond  weighing  125^  carats;  the  "Star  of  South  Africa,"  already 
mentioned  as  found  in  1869,  and  now  cut  to  a  size  of  46^  carats; 
and  the  "Victoria,"  a  stone  of  180  carats,  cut  from  an  octahedron 
weighing  457^  carats. 

Turning  to  a  consideration  of  the  geological  characters  of  the  dia- 
mond-bearing areas,  it  may  be  stated  that  each  is  approximately  spheri- 
cal or  oval  in  form,  with  an  average  diameter  of  two  hundred  to  three 
hundred  yards.  The  four  principal  mines  are  embraced  within  an  area 
four  miles  square.  The  areas  in  which  the  diamonds  were  found  were 
originally  somewhat  depressed,  giving  to  them  the  name  of  "pans."  The 
upper  portion  of  the  area  was  a  friable  mass  of  a  yellow  color  called 
"yellow  ground."  On  going  deeper  the  color  of  this  portion  changed 
to  a  blue  or  greenish  blue,  and  the  rock  became  firmer.  It  is  this 
"  blue "  or  "  blue  ground "  which,  now  that  the  yellow  ground  has 
become  exhausted,  furnishes  all  the  diamonds.  The  strata  which  inclose 
it  are,  as  illustrated  in  the  accompanying  figure,  at  the  top,  a  layer  of 
basalt  about  fifty  feet  in  thickness ;  below  this  two  hundred  to  three 
hundred  feet  of  a  nearly  horizontal  black,  carbonaceous  shale;  next 
a  thin  conglomerate;  next  about  four  hundred  feet  of  a  dark  rock 
called  at  first  melaphyre,  but  now  regarded  as  olivine  diabase;  and 
finally  a  quartzite  which  extends  as  far  as  exploration  has  gone.  The 
relation  of  the  diamond-bearing  ground  to  these  strata  seems  to  be  in 
the  nature  of  a  volcanic  intrusion.  The  diamond-bearing  or  "  blue 

83 


ground  "  is  a  breccia,  consisting  largely  of  chrysolite  more  or' less  altered 
to  serpentine,  and  accompanied  by  bronzite,  pyrope,  diopside,  zircon? 
cyanite,  mica,  pyrite,  magnetite,  ilmenite,  and  some  other  minerals. 
There  are  also  fragments  of  shale  and  boulders  of  varying  composition 
in  the  blue  ground. 

The  origin  of  the  diamonds  in  the  blue  ground  has  naturally  been 
the  source  of  much  speculation,  but  no  theory  meets  general  accept- 
ance as  yet.  One  of  the  first  suggestions  was  that  of  Professor  Henry 
Carvill  Lewis,  of  Philadelphia,  that  the  heat  of  the  volcanic  intrusion 


Section  of  De  Beers  diamond  mine,  South  Africa,  showing  character  of  strata.     The  "blue 

ground  "  is  the  diamond-bearing  area 

transformed  the  carbon  of  the  surface  shales  into  diamond.  This  theory 
seems  untenable,  however,  for  many  reasons,  as  shown  by  Mr.  Gardner 
F.  Williams  in  his  recent  work.  Mr.  Williams  states  that  about  the 
diamond-bearing  deposits  at  Jagersfontein  there  are  no  such  shales, 
while  in  the  regions  where  they  do  exist  there  is  no  alteration  observ- 
able at  the  junction  of  the  shales  and  blue  ground,  nor  among  the 
fragments  of  shale  inclosed  in  the  blue.  According  to  another  theory 
the  blue  ground  is  not  of  igneous  origin,  but  is  a  sort  of  mud  forced 
up  by  hydrostatic  pressure.  This  brought  up  the  diamonds  from  depths 
below.  The  present  trend  of  opinion  seems  to  be  that  the  origin  of  the 
diamond  was  deep-seated;  but  whether  its  matrix  was  the  basic  rock 
in  which  it  is  now  found  or  some  other  is  not  known.  Professor 
T.  G.  Bonney,  who  has  given  much  attention  to  the  matter, ,  is  of  the 

84 


opinion  that  the  diamonds  were  originally  connected  with  eclogite, 
a  metamorphic  rock  carrying  somewhat  more  silica  than  character- 
izes the  present  blue  ground,  and  containing  considerable  garnet. 

About  ninety-five  per  cent  of  the  world's  supply  of  diamonds  comes 
at  the  present  time  from  the  South  African  mines,  their  annual  pro- 
duction being  about  2,500,000  carats.  Other  countries  which  produce 
small  quantities  of  diamonds,  besides  those  already  mentioned,  are 
Borneo,  Australia,  British  Guiana,  and  the  United  States. 

The  diamonds  of  Borneo  come  from  two  portions  of  the  island, 
one  field  being  in  the  western  and  the  other  in  the  southern  part. 
These  fields  have  been  known  and  worked  from  time  immemorial; 
but  have  afforded  only  a  small  supply,  the  product  varying  from 
twro  thousand  to  six  thousand  carats  annually.  In  the  western  part 
of  the  island  the  diamonds  occur  in  alluvial  gravels,  and  their  parent 
rock  is  not  known.  In  the  southern  part  they  occur  in  a  conglomer- 
ate overlying  strata  of  Eocene  age.  The  majority  of  the  diamonds 
obtained  are  small  and  of  rather  poor  quality.  Their  mining  is  per- 
formed in  a  desultory  way  by  native  Malays  and  Chinese,  and  the 
supply  seems  gradually  to  be  decreasing. 

The  first  discovery  of  diamonds  in  Australia  was  made  in  1851  in 
placer  gold-mining  in  New  South  Wales.  The  locality  was  not  far 
from  Bathurst.  Since  then  in  this  locality,  and  the  neighboring  head 
waters  of  the  Macquarie  River,  a  number  of  small  diamonds  have  been 
found.  The  largest  number  were  found  along  the  Cudgegong  River, 
northwest  of  Mudgee,  in  an  old  river  drift  covered  with  basalt.  About 
2,500  stones  were  obtained  there  in  1869.  Accompanying  the  dia- 
monds are  gold,  garnet,  zircon,  tinstone,  or  cassiterite,  tourmaline,  and 
magnetite.  The  gold  and  diamonds  are  obtained  as  in  California  by 
tunneling  under,  the  basalt  so  as  to  excavate  the  gravels.  Another 
locality  in  New  South  Wales  which  has  yielded  diamonds  is  in  the 
vicinity  of  Bingera.  Here  the  diamonds  occur  in  gold  and  ruby-bearing 
sands,  the  accompanying  minerals  being  quite  similar  to  those  men- 
tioned above. 

In  Southern  and  Western  Australia  and  in  Tasmania  a  few  dia- 
monds have  also  been  found.  The  Australian  diamonds  are  all  small, 
none  of  over  6  carats  weight  being  known.  The  yield  from  New  South 
Wales  in  1899  was  reported  to  be  25,874  carats. 

Small  diamonds  have  been  found  at  several  points  in  the  Ural  Moun- 
tains. The  first  were  obtained  about  1829  in  the  vicinity  of  Bissersk, 
Government  of  Perm,  occurring  in  alluvial  sands  with  gold,  platinum, 
quartz,  magnetite,  and  anatase.  It  is  said  that  Alexander  Humboldt 

85 


predicted  the  finding  of  diamonds  here  from  the  similarity  of  the 
gravels  to  those  of  Brazil  in  which  diamonds  are  obtained. 

Later  finds  of  diamonds  have  been  made  near  Ekaterinburg  and 
in  Werchne  Uralsk  and  Troitzk  in  the  Government  of  Orenburg; 
likewise  in  connection  with  auriferous  sands. 

Diamonds  have  also  been  found  in  Lapland  in  the  vicinity  of  Var- 
anger  Fjord  on  the  Arctic  Sea.  They  occur  in  river  sands,  together 
with  garnet,  quartz,  rutile,  and  other  minerals  usually  found  accom- 
panying diamond.  These  diamonds  are  small  and  scarce. 

British  Guiana  has  recently  come  into  prominence  as  a  field  which 
may  produce  a  profitable  supply  of  diamonds.  Small  stones  were  first 
found  here  about  1890,  and  work  has  been  continued  until  now  a  con- 
siderable amount  of  mining  is  carried  on.  The  locality  is  along  the 
Upper  Mazaruni  River,  two  hundred  and  fifty  miles  south  of  the  town 
of  Bartica.  The  journey  to  it  is  a  long  and  difficult  one,  all  supplies 
requiring  to  be  transported  over  a  narrow  trail  through  a  tropical 
jungle.  The  diamonds  occur  in  a  formation  of  sandy  clay  with  other 
pebbles  and  ironstone  nodules.  They  are  separated  by  washing  the  clay 
in  sieves  of  one-sixteenth  inch  mesh  to  remove  the  fine  particles,  and 
are  then  picked  out  by  hand.  The  yield  is  quite  remunerative,  nine 
men  having  in  one  instance  obtained  four  hundred  stones  by  working 
eighteen  days.  The  stones  are  small  in  size,  few  being  above  two  carats 
weight,  but  they  are  of  good  quality.  Several  companies  have  been 
organized  to  work  the  deposits,  and  a  measurable  output  is  likely  to  be 
obtained. 

The  occurrence  of  diamonds  in  the  United  States  is  largely  confined 
to  two  regions ;  the  first  a  belt  of  country  lying  along  the  eastern  base 
of  the  southern  Alleghanies  from  Virginia  to  Georgia,  while  the  other 
extends  along  the  western  base  of  the  Sierra  Nevada  and  Cascade 
ranges  in  northern  California  and  southern  Oregon.  There  is  also 
a  third,  of  less  importance,  belonging  to  the  Kettle  moraine  district 
of  southern  Wisconsin.  One  of  the  diamonds  found  in  the  southern 
Alleghanies  weighed  23f  carats.  It  was  found  in  1855  at  Manchester, 
Virginia,  and  is  usually  known  as  the  Dewey  diamond  from  the  name 
of  its  one-time  owner.  Eight  or  ten  diamonds,  varying  from  one  to  four 
carats  in  weight,  have  been  found  in  various  localities  in  North  Carolina ; 
ten  or  twelve  counties  in  Georgia  have  furnished  one  or  more  small 
stones,  and  one  or  two  are  reported  from  South  Carolina.  These  dia- 
monds have  all  been  found  loose  in  gravels,  and  have  been  obtained 
either  while  washing  the  gravels  for  gold,  or  in  digging  wells,  or  they 
have  been  picked  up  by  children.  A  resemblance  of  certain  strata  in 


GLACIAL  MAP  OF  THE  GREAT  LAKES  REGION. 


M!orai.n.a». 
Diamond    Localities 


Ol.de  IT    Dvi  I  L. 

X    ^ 
Glaoial  Striae  . 


Newer-    Drii  t 

Ti-a.cls.oE  Diai-n.oi-vd6. 
El, Eagle.          O,  Oregon, 
i-ii    Cvlf..     B  Surlin.(i,toi-L 


North  Carolina  to  the  itacohnnite  of  Brazil,  in  which  diamonds  are 
found,  has  at  times  been  urged  as  indicating  that  these  may  have 
been  the  source  of  the  diamonds,  but  no  discovery  of  such  stones  has 
yet  been  made  in  this  formation.  The  diamonds  of  the  Kettle  moraine 
region  of  southern  Wisconsin  have  all  been  discovered  since  1876. 
They  have  been  obtained  at  six  localities  in  Wisconsin,  and  one  locality 
each  in  Michigan  and  Ohio.  Seven  good-sized  diamonds  have  been  found, 
the  largest  weighing  21^  carats,  and  one  locality  has  yielded  numerous 
small  stones.  The  diamonds  were  obtained  in  gravels  of  glacial  origin, 
and  Hobbs  has  shown,  from  a  study  of  the  directions  of  glacial  move- 
ment, that  the  original  source  of  the  gems  may  have  been  the  territory 
lying  southwest  and  south  of  Hudson's  Bay.  The  localities  where  the 
diamonds  were  found,  and  the  probable  course  of  their  distribution 
southward,  are  shown  on  the  accompanying  map. 

The  diamonds  of  California  have  been  found  in  connection  with  . 
gold-bearing  gravels,  the  gravels  being  sometimes  those  buried  under 
lava  flows.  In  Amador,  Butte,  El  Dorado,  Nevada,  and  Trinity  counties 
diamonds  have  been  found,  the  stones  rarely  exceeding  two  carats  in 
weight,  but  being  generally  of  excellent  quality.  The  accompanying 
minerals  have  been  zircon,  topaz,  quartz,  epidote,  pyrite,  chromite,  etc. 
The  diamonds  are  discovered  in  washing  for  gold;  but  the  yield  has 
never  been  sufficient  to  repay  search  for  them  alone,  nor  is  it  likely 
ever  to  be.  In  one  or  two  localities  in  Oregon,  Idaho,  and  Montana 
diamonds  have  been  similarly  obtained. 

Numerous  attempts  have  been  made  to  produce  the  diamond  artifi- 
cially, some  of  which  have  been  attended  with  success,  although  no  stones 
large  enough  for  industrial  or  ornamental  use  have  yet  been  made. 

Moissan,  of  Paris,  in  1893  succeeded  in  producing  diamonds  by  heat- 
ing iron  saturated  with  carbon  to  a  high  temperature,  and  then  sud- 
denly cooling  the  exterior  of  the  mass.  This  exterior  cooling  caused 
an  intense  pressure  on  the  interior,  whence  black  diamonds  of  micro- 
scopic size  were  produced  as  a  result  of  the  heat  and  pressure,  as  it 
is  believed. 

Still  more  recently,  von  Hasslinger  has  obtained  diamonds  by  fusing 
a  mixture  corresponding  in  composition  to  the  South  African  diamond- 
bearing  breccias.  The  diamonds  were  small,  not  exceeding  .002  of  an 
inch  in  diameter,  but  they  were  colorless  and  transparent  crystals. 
The  success  of  these  experiments  gives  some  reason  to  believe  that 
fair-sized  diamonds  may  in  time  be  produced  artificially. 


87 


CORUNDUM 

(RUBY,  SAPPHIRE,  ETC.) 

The  mineral  species  corundum  affords  a  number  of  gems  known  by 
different  names  because  the  stones  were  used  as  gems  before  their  miner- 
alogical  identity  was  discovered.  Thus  the  ruby  is  red  corundum  and 
sapphire  blue  corundum.  When  corundum  suitable  for  gem  purposes 
occurs  of  other  colors,  such  as  green,  yellow,  or  violet,  the  gems  are 
sometimes  known  as  green,  yellow,  or  violet  sapphires,  respectively, 
or  by  the  name  of  another  gem  which  they  closely  resemble  in  color, 
with  the  adjective  "Oriental"  prefixed.  Such  are  the  gems  known 
as  Oriental  topaz,  Oriental  emerald,  Oriental  aquamarine,  Oriental  hya- 
cinth, Oriental  amethyst,  and  Oriental  chrysolite.  Colorless  corundum 
is  known  as  leucosapphire.  While  corundum  of  all  colors  is  used  for 
gems,  it  is  only  that  which  is  transparent  which  can  be  so  employed. 
This  is  sometimes  called  noble  corundum  to  distinguish  it  from  common 
corundum.  The  two,  however,  often  occur  together.  Common  corundum 
is  used  as  an  abrasive,  emery  being  one  of  its  varieties,  but  it  has  no 
gem  value. 

Corundum  is  a  sesquioxide  of  aluminum,  with  the  percentages,  alumina 
53.2,  oxygen  46.8.  Its  hardness  is  9  in  the  scale,  and  no  mineral  except 
the  diamond  equals  it  in  this  respect.  This  hardness  gives  it  a  wear- 
ing quality  as  a  gem  second  only  to  the  diamond.  The  varieties 
of  corundum  differ  slightly  in  hardness,  sapphire  being  the  hardest. 
Noble  corundum  has  a  brilliant,  vitreous  luster,  which,  while  not  equal 
to  that  of  the  diamond,  is  superior  to  that  exhibited  by  almost  any 
other  gem.  Corundum  is  a  heavy  mineral,  its  specific  gravity  being 
four  times  that  of  water.  This  high  specific  gravity  affords  an  easy 
means  of  distinguishing  gems  of  corundum  from  those  of  other  species. 
Corundum  is  infusible,  and  is  not  attacked  by  acids.  It  crystallizes  in 
the  rhombohedral  division  of  the  hexagonal  system,  certain  crystal  forms 
being  characteristic  of  the  two  varieties,  ruby  and  sapphire.  Thus  ruby 
tends  to  crystallize  in  flat  rhombohedral  crystals,  while  sapphire  generally 
forms  in  longer  hexagonal  prisms.  (See  colored  plate.)  Corundum 
is  doubly  refracting  and  dichroic.  Of  the  different  colors  of  corundum 
above  referred  to,  the  blue  or  sapphire  is  most  common,  the  red  or  ruby 

88 


next.  The  other  colors  occur  rather  sparingly,  green  having  been  almost 
unknown  until  the  discovery  of  the  Montana  sapphires.  The  nature  of 
the  coloring  ingredient  of  the  different  varieties  of  corundum  is  not 
known,  but  there  is  some  reason  for  believing  it  to  be  chromium,  for 
Fremy  obtained  artificial  red  and  blue  corundum  by  mixing  chromium 
with  his  other  ingredients,  after  many  other  attempts  to  obtain  the 
desired  color  had  failed. 

Red  corundum  varies  in  hue  from  rose  to  deep  red.  That  of  the 
latter  tint  is  the  true  ruby,  the  color  known  as  pigeon's  blood  being  most 
highly  prized.  Faultless  stones  of  this  color  have  long  been  the  most 
valuable  of  gems,  exceeding  the  diamond  in  price,  weight  for  weight. 
At  the  present  time  they  are  worth  between  $2,000  and  $3,000  per 
carat.  The  writer  recently  saw  a  ruby  of  nine  carats  in  the  possession 
of  a  Chicago  jeweler  which  is  valued  at  $25,000,  and  one  of  eleven 
carats  is  reported  to  have  been  lately  sold  for  $80,000.  But  few  rubies 
exceeding  ten  carats  are  known.  The  King  of  Pegu  is  reported  to  have 
one  the  size  of  a  hen's  egg,  but  as  no  one  has  ever  seen  it  the  story 
may  well  be  doubted.  In  the  crown  of  the  Empress  Catherine  was,  how- 
ever, one  the  size  of  a  pigeon's  egg.  There  is  also  a  large  uncut  ruby  in 
the  British  crown,  said  to  have  been  given  to  Edward,  Prince  of  Wales, 
by  the  King  of  Castile,  in  1367.  Ruskin  calls  it  the  loveliest  precious 
stone  of  which  he  has  any  knowledge.  This  is  probably,  however,  a 
spinel  ruby,  not  a  corundum  ruby. 

The  chief  home  of  the  true  ruby  is  Burmah.  From  its  mines  and 
those  of  Siam  and  Ceylon  have  come  practically  all  the  world's  supply. 
The  most  important  Burmese  mines  are  in  Mogouk,  ninety  miles  north 
of  Mandalay.  The  rubies  were  evidently  formed  here  in  limestone,  which 
is  now  much  decomposed,  and  seem  to  have  been  the  result  of  metamor- 
phism  of  the  limestone  by  the  entrance  of  eruptive  rocks.  The  ruby- 
bearing  earth  is  known  as  "  by  on,"  and  the  gems  are  obtained  from 
it  by  washing.  They  are  usually  in  the  form  of  more  or  less  complete 
crystals.  The  mines  have  been  worked  since  the  British  occupation 
of  Burmah  in  1886,  by  a  British  company,  and  there  can  be  little  doubt 
that  a  desire  to  acquire  these  mines  was  one  reason  for  the  occupation. 
The  mines  have  not  proved  very  profitable,  however,  and  only  within  the 
last  year  or  two  has  the  company  been  able  to  pay  any  dividends.  The 
hope  of  success  has  lain  in  the  introduction  of  machinery  for  washing 
the  byon  more  cheaply  than  it  could  be  done  by  the  primitive  native 
methods,  and  it  is  now  believed  by  the  introduction  of  an  electrical 
power  plant  that  this  has  been  accomplished.  This  company  now  pro- 
duces at  least  one-half  the  annual  yield  of  rubies  of  the  world. 

89 


Bed  of  ruby-bearing  gravel  at  Caler  Fork,  Cowee  Valley,  Macon  County,  North  Carolina 


Washing  gravel  for  rubies,  Cowee  Valley,  Macon  County,  North  Carolina 

90 


Previous  to  the  working  of  the  mines  by  the  English  the  mining 
was  performed  by  domestic  labor  under  control  of  the  native  govern- 
ment, all  rubies  above  a  certain  size  going  to  the  king.  Whenever 
a  ruby  of  unusual  size  was  found  a  procession  of  grandees,  with  soldiers 
and  elephants,  was  sent  out  to  meet  it.  One  of  the  titles  of  the  King 
of  Burmah  was  Lord  of  the  Rubies. 

£-The  Siamese  rubies  come  from  near  Bangkok,  on  the  Gulf  of  Siam. 
They  occur  in  a  clay  which  seems  to  be  the  product  of  alteration  of  a 
basalt.  These  rubies  are  not  equal  in  quality  to  those  of  Burmah. 
Rubies  are  also  found  in  the  gem  gravels  of  Ceylon,  and  in  Afghanistan, 
thirty-two  miles  east  of  Cabul. 

In  our  own  country  ruby  corundum  is  occasionally  found  in  connec- 
tion with  opaque  corundum  in  Macon  County,  North  Carolina.  In  the 
gravels  of  Caler  Fork  of  Cowee  Creek  of  this  county  good  rubies  are 
found  in  sufficient  quantity  to  reward  systematic  mining  for  them. 
They  are  known  as  "Cowee  Creek"  rubies. 

The  gravels  containing  them  are  "  washed"  by  methods  described  by 
Dr.  J.  H.  Pratt  as  similar  to  those  used  in  the  West  for  washing  gold- 
bearing  gravels.  Both  the  gravel  and  the  soil  which  overlies  it  are 
washed  into  a  line  of  sluice  boxes  which  lead  into  a  sieve  box.  From 
the  latter  the  dirt  and  fine  gravel  are.  washed  away.  The  material  that 
remains  is  shoveled  into  a  rocker,  into  the  bottom  of  which  the  rubies, 
being  heavier,  gradually  work,  and  are  then  removed  by  hand  picking. 
These  rubies  are  mostly  small,  but  some  gems  of  three  or  four  carats' 
weight  and  of  excellent  color  have  been  obtained. 

Among  the  Montana  sapphires  an  occasional  red  stone  is  found,  but 
they  do  not  have  the  choicest  red  color. 

Another  source  of  rubies  is  their  artificial  production,  after  the  method 
discovered  by  the  French  chemist  Fremy.  The  artificial  rubies  are  made 
by  heating  a  mixture  of  aluminum  sesquioxide,  carbonate  of  lime,  barium 
fluoride,  and  potassium  chromate  in  a  porous  clay  crucible  to  a  tem- 
perature of  1500°  C.,  and  keeping  the  mixture  fluid  for  eight  days. 
Well -formed,  clear  crystals  up  to  one -third  of  a  carat  in  weight 
tre  thus  produced,  which  have  the  hardness  and  color  of  native  ruby. 
They  are  not  considered  so  valuable  as  gems  as  the  latter,  and  can 
usually  be  distinguished  by  the  minute  air  bubbles  which  they  contain. 
The  expense  of  making  them  is  nearly  equal  to  the  value  of  native 
rubies,  so  that  their  production  is  likely  to  be  limited. 

Other  substitutes  for  the  ruby  are  garnet,  that  from  South  Africa 
being  known  as  Cape  ruby,  hyacinth,  red  tourmaline,  known  as  Siberian 
ruby,  rose  topaz,  sometimes  known  as  Brazilian  ruby,  and  spinel.  None 

91 


of  these  is  as  hard  as  the  ruby,  and  each  differs  sufficiently  from  the 
ruby  in  its  refractive  powers,  or  specific  gravity,  to  make  distinc- 
tion easy. 

Rubies  were  known  to  the  ancients,  being  mentioned  in  the  Bible  in 
Proverbs  and  Job.  The  Greeks  and  Romans  ascribed  to  the  ruby  the 
power  of  giving  light  in  the  dark,  and  the  Hindoos  describe  the  abodes 
of  their  gods  as  thus  lighted.  The  ruby  was  much  worn  as  an  amulet, 
being  supposed  to  protect  the  wearer  against  plague,  poison,  and  evil 
spirits.  It  was  also  thought  that  it  would  turn  dark  if  its  owner 
were  in  danger,  and  would  not  regain  its  color  until  the  peril  was 
over.  The  Burmese  believe  that  the  ruby  ripens  like  fruit.  The  crude 
are  colorless;  thence  they  grade  yellow,  green,  blue,  red. 

The  ruby  is  usually  cut  in  the  form  of  the  brilliant,  like  the  dia- 
mond, but  sometimes  the  step  cut  is  advantageously  employed.  The 
native  gem -cutters  of  India  do  not  cut  facets  on  their  rubies,  but 
simply  round  and  polish  them. 

Blue,  precious  corundum,  or  sapphire,  is  more  abundant  than  the 
red  or  ruby.  Like  the  red,  the  blue  color  seems  to  be  due  to  a  con- 
tent of  chromium,  since  in  the  artificial  crystals  already  mentioned 
as  produced  by  Fremy,  both  colors  occur  at  times  in  the  same  crystal. 
This  occurrence  of  two  colors  in  single  crystals  is  also  found  in 
Nature,  some  being  red  at  one  end  and  blue  at  the  other;  or,  perhaps 
what  is  more  frequent,  the  center  of  the  crystal  may  be  yellow  and 
the  exterior  blue.  This  coloring  is  not  uncommon  among  the  Australian 
sapphires,  and  unique  gems  are  obtained  by  cutting  them  so  as  to  show 
the  two  colors.  Bauer  describes  a  figure  of  Confucius  carved  from 
a  sapphire,  of  which  the  head  is  white,  the  trunk  and  arms  blue,  and 
the  legs  yellow.  The  color  of  sapphire  most  highly  prized  is  that 
known  as  cornflower-blue.  The  cornflower  (Centaurea  cyanus)  is  also 
known  in  this  country  by  the  name  of  "  bachelor's  button,"  and  excel- 
lently typifies  the  true  sapphire  color.  Other  shades  of  blue  which 
occur  in  the  sapphire,  are  indigo-blue,  smalt-blue,  berlin-blue,  and 
greenish  and  grayish  blues.  The  sapphires  of  darker  colors  are  usually 
known  as  male  and  those  of  lighter  colors  as  female  sapphires.  In 
addition  to  possessing  the  true  corn-flower  blue  color,  the  best  sapphires 
should  exhibit  a  velvety  sheen,  the  value  of  the  stone  being  greater 
the  more  perfect  this  character. 

As  already  noted,  sapphire  is  somewhat  harder  than  ruby,  and  it 
is  also  somewhat  heavier.  The  Montana  sapphires  are  said  to  be  espe- 
cially hard. 

Sapphires  have  at  the  present  time  not  over  half  the  value  of  a  ruby 

92 


Corundum  mine  from  which  some  sapphire  is  obtained 
Corundum  Hill,  Macon  County,  North  Carolina 


of  the  same  size.  A  price  of  forty  dollars  per  carat  is  an  average  one 
for  a  small  stone;  and  as  much  larger  stones  are  comparatively 
common,  the  price  does  not  increase  so  rapidly  as  does  that  of  the 
ruby  with  an  increase  in  size. 

The  world's  supply  of  sapphires  comes  chiefly  from  Siam.  The  most 
important  mines  of  that  country  are  those  of  Battambong,  a  city  south- 
east of  Bangkok.  The  sapphires  occur  in  a  sandy  clay,  out  of  which 
they  are  washed.  The  sapphire-bearing  region  is  about  a  hundred  miles 
in  length.  Together  with  the  sapphires  occur  some  rubies,  especially 
in  the  southern  part  of  the  district.  Sapphires  also  occur  among  the 
rubies  of  Bur  mail,  but  in  small  numbers.  The  so-called  gem  gravels 
of  Ceylon  furnish  many  sapphires,  though  their  quality  is  not  equal 
to  those  of  Siam,  because  of  paleness  of  color. 

Another  locality  for  sapphires,  discovered  about  1882,  is  Banskar, 
in  Cashmere,  India.  These  stones  were  first  disclosed  by  the  fall  of  an 
avalanche,  and  later  were  discovered  to  exist  in  the  region  in  consider- 
able numbers.  For  a  time  they  could  be  cheaply  purchased,  but  are 
now  jealously  guarded  by  the  government. 

The  Montana  sapphires  have  been  known  since  1865,  but  were  not 
systematically  worked  until  1891.  They  occur  in  river  sands  east 
of  Helena,  and  were  first  obtained  in  washing  for  gold.  Now  the 
mother  rock  has  been  discovered;  and  this  is  mined,  the  rock  being 
taken  out,  piled  in  heaps,  and  submitted  to  the  action  of  frost  through 
the  winter.  The  sapphires  thus  become  loosened  and  can  be  readily 
separated.  These  sapphires  are  well  crystallized  and  are  of  good  aver- 
age size,  though  few  gems  exceed  six  carats  in  weight.  Their  luster 
and  color  are  for  the  most  part  of  first  quality,  and  the  stones  are  in 
demand  for  the  best  of  jewelry.  The  most  recent  find  of  sapphires 
has  been  in  Central  Queensland,  Australia,  at  a  place  called  "^Anakie, 
twenty -six  miles  west  of  Emerald.  Here  sapphires  occur  over  an 
extensive  area.  Green,  yellow,  pale  blue,  and  dark  blue  stones  are 
those  most  commonly  found,  the  cornflower-blue  occurring  but  rarely. 
Hence,  the  stones  have  not  been  widely  used  as  yet.  They  reach  sizes 
of  from  thirty  to  fifty  carats. 

The  common  corundum  of  North  Carolina,  mined  extensively  as  an 
abrasive,  often  also  contains  blue  transparent  portions  from  which  gems 
can  be  made.  One  of  the  best  known  mines  yielding  such  stones  is  that 
at  Corundum  Hill,  in  Macon  County.  This  also  produces  a  few  rubies, 
and  a  fine  specimen  of  Oriental  emerald,  or  green  sapphire,  was  obtained 
here.  This  was  a  crystal  4  by  2  by  1 3-  inches,  which  would  afford 
several  first-class  gems. 


Noble  corundum  of  other  colors  than  those  of  blue  and  red  is  not 
of  abundant  occurrence,  nor  is  it  ordinarily  as  highly  prized  as  are 
the  sapphire  and  ruby.  Colorless  sapphire,  or  leucosapphire,  is  some- 
times used  as  a  substitute  for  the  diamond,  from  which  it  can  readily 
be  distinguished  by  its  lower  hardness  and  higher  specific  gravity. 

Certain  specimens  of  both  sapphire  and  ruby,  but  especially  the 
former,  exhibit  when  polished  a  six-rayed  star.  This  appears  as  beams 
of  light,  radiating  from  a  center  which  changes  in  position  as  the  stone 
is  turned.  Such  stones  are  called  star,  or  asteriated  sapphires,  or  rubies, 
and  are  highly  prized.  They  are  usually  cut  with  rounded  surface, 
as  this  best  brings  out  the  figure.  The  cause  of  the  star-shaped  figure 
is  generally  supposed  to  be  the  total  reflection  of  light  from  countless 
microscopic  cavities  in  the  stone,  which  are  arranged  parallel  to  the 
faces  of  a  six-sided  prism.  Some  authorities  believe,  however,  that  mul- 
titudes of  twining  lamellae  similarly  arranged  cause  the  appearance. 

Burton,  the  African  traveler,  is  said  always  to  have  carried  a  star 
sapphire  about  with  him,  as  a  means  of  winning  respect  from  the 
barbarous  peoples  among  whom  he  journeyed.  The  savages  believed 
that  the  stone  must  be  a  talisman  of  great  power  and  feared  to  incur 
its  owner's  enmity. 

Sapphire  is  a  word  which  is  the  same  in  nearly  all  languages, 
a  fact  which  testifies  to  the  ancient  use  of  the  stone.  In  Chaldean, 
Hebrew,  Greek,  and  Latin  the  word  has  the  same  form  as  in  mod- 
ern tongues.  In  early  times  sapphire  was  believed  to  be  a  destroyer 
of  poison,  so  that  if  put  into  a  glass  with  a  spider  or  venomous  reptile 
it  would  kill  it.  It  was  regarded  also  as  a  remedy  against  fevers 
if  placed  on  the  heart,  or  soaked  in  vinegar  and  the  extract  admin- 
istered. The  wearer  of  a  sapphire  was  rendered  by  it  chaste,  virtuous, 
pious,  devout,  and  wise. 


SPINEL 

(RUBY  SPINEL,   BALAS    RUBY) 

The  group  of  spinel  includes  in  mineralogy  a  number  of  species  of 
different  though  analogous  composition.  The  spinel  employed  as  a  gem 
is  almost  wholly  a  magnesium  aluminate,  having  the  percentage  composi- 
tion: alumina  71.8  and  magnesia  28.2.  This  is  usually  of  a  red  color, 
different  shades  giving  gems  known  by  different  names  as  follows  :  Deep 
red,  spinel-ruby;  rose-red,  balas  ruby;  yellow  or  orange  red,  rubicelle; 
violet-red,  almandine  ruby.  Spinel  is  thus  known  among  gems  chiefly 
as  a  relative  of  the  ruby,  and  this  sort  of  spinel  will  first  be  con- 
sidered. 

The  spinel  rubies  differ  from  the  true  or  corundum  rubies  in  hard- 
ness, specific  gravity,  and  system  of  crystallization.  The  hardness  of 
spinel  is  8,  or  about  that  of  topaz,  and  the  specific  gravity  3.6.  It  is 
thus  neither  as  hard  nor  as  heavy  as  corundum  ruby.  Again,  the  system 
of  crystallization  differs.  Spinel  crystallizes  in  the  isometric  system,  and 
is  usually  found  in  the  form  of  octahedrons,  while  corundum  ruby  is 
hexagonal  in  crystallization.  (See  colored  plate.)  Spinel  is  singly  refract- 
ing in  polarized  light,  and  corundum  doubly  refracting.  Spinel  ruby  is 
infusible  before  the  blowpipe,  but  on  heating  undergoes  a  curious  series 
of  changes  in  color  which  are  quite  characteristic.  The  red  changes 
first  to  brown,  and  then  becomes  black  and  opaque,  but  on  cooling  the 
black  changes  to  green,  then  becomes  nearly  colorless,  and  finally  the 
stone  resumes  its  original  red  color.  As  a  small  percentage  of  chro- 
mium is  usually  found  by  analysis  to  exist  in  ruby  spinel,  its  color  is 
generally  considered  to  be  due  to  this  ingredient.  While  the  spinel  ruby 
is  considered  of  less  value  than  the  corundum  ruby,  and  is  sometimes  by 
fraud  or  error  substituted  for  the  latter,  it  yet  has  a  definite  value  as  a 
gem  when  sold  under  the  name  of  spinel  ruby  or  some  of  its  varieties. 
This  value  is  usually  reckoned  at  about  half  that  of  the  corundum  ruby, 
although  variations  in  quality  of  the  stones,  as  well  as  changes  in  demand, 
cause  differences  of  price.  Thus  Emanuel  mentions  a  spinel  ruby  of  good 
quality  weighing  40  carats,  which  in  1856  was  sold  for  $2,000,  but 
in  1862  brought  at  public  auction  only  $400.  In  1866,  however,  it  was 
again  sold  for  $1,200.  A  spinel  ruby  among  the  French  crown  jewels, 

95 


weighing  56  carats,  was  in  1791  valued  at  $10,000.  This  is  much  more 
than  such  a  stone  would  now  probably  be  worth. 

Not  only  is  spinel  ruby  related  to  corundum  ruby  in  color  and  use, 
but  the  two  are  frequently  associated  together  in  nature.  The  gem 
gravels  of  Ceylon,  Siam,  Australia,  and  Brazil  contain  both  kinds  of 
rubies,  and  the  ruby  mines  of  Upper  Burmah,  where  the  corundum  ruby 
occurs  in  a  crystalline  limestone,  produce  also  large  quantities  of  spinel 
rubies.  Spinel  rubies  also  come  in  large  quantity  from  'Badakschan,  in 
Afghanistan,  near  the  river  Oxus,  the  name  of  balas  rubies,  by  which 
they  are  often  known,  being  said  to  be  derived  from  Beloochistan, 
another  form  of  which  word  is  Balakschan.  The  Persians  have  a  tradi- 
tion regarding  these  mines,  that  they  were  disclosed  by  an  earthquake 
which  rent  the  mountain  in  twain. 

The  localities  above  mentioned  furnish  nearly  all  the  spinel  rubies 
of  commerce.  A  few  have  been  found  in  North  America,  Hamburgh, 
New  Jersey,  and  San  Luis  Obispo,  California,  being  two  localities  where 
small  crystals  have  been  obtained,  but  they  have  never  afforded  any 
appreciable  supply.  No  spinel  rubies  of  great  size  are  known.  Bauer 
mentions  as  the  largest  known,  two  cut  stones,  one  of  81  carats,  and 
the  other  72^  carats,  exhibited  at  the  London  Exposition  of  1862.  The 
King  of  Oude  is  said  at  one  time  to  have  possessed  a  spinel  ruby  the  size 
of  a  pigeon's  egg.  Another  celebrated  spinel  ruby  is  that  known  as  the 
•'  Ruby  of  the  Black  Prince,"  which  is  shown  among  the  English  crown 
jewels  in  the  Tower  of  London. 

Spinel  occurs  in  many  other  colors  besides  red,  such  as  orange,  green, 
blue,  and  indigo,  as  well  as  white  and  black.  Occasionally  colorless 
spinels  occur,  and  as  they  cannot  be  distinguished  by  their  behavior  in 
polarized  light  from  the  diamond,  it  is  sometimes  sought  to  substitute 
them  for  the  latter.  They  can  be  detected  at  once,  however,  by  their 
inferior  hardness.  While  spinels  of  any  color,  if  transparent  and  free 
from  flaws,  make  desirable  gems,  the  only  colors  found  in  sufficient  quan- 
tity outside  of  the  red  to  make  an  appreciable  supply  are  the  blue  and  the 
black.  The  blue  spinels  resemble  the  sapphire  in  color,  though  they  are 
somewhat  paler.  They  come  chiefly  from  Ceylon  and  Burmah,  where 
they  occur  together  with  the  ruby  spinel.  The  black  spinel  is  known  as 
ceylonite,  or  pleonaste,  and  is  also  obtained  chiefly  from  Ceylon,  although 
occurring  of  a  quality  suitable  for  cutting  at  Mount  Vesuvius  in  Italy. 

Like  the  ruby,  spinel  can  be  made  artificially,  the  process  being  to 
heat  a  mixture  of  alumina  and  magnesia  with  boracic  acid,  and  if  a  red 
color  is  desired,  a  little  chromium  oxide.  No  attempt  seems  to  have  been 
made  as  yet,  however,  to  manufacture  it  for  gem  purposes. 

96 


The  spinel  ruby  seems  to  have  been  known  to  the  ancients  equally 
with  the  corundum  ruby,  and  the  two  were  probably  often  confounded. 
The  natives  of  India  call  the  spinel  the  pomegranate  ruby,  and  believe 
to  this  day  that  it  possesses  valuable  medicinal  properties. 

In  the  Middle  Ages  it  was  believed  that  if  one  touched  with  this 
gem  the  four  corners  of  a  house,  orchard,  or  vineyard  they  would  be 
protected  from  lightning,  storms,  and  blight. 

The  Arabs  had  a  tradition  that  sea  cows  gathered  spinels  from  the 
Kokaf  Mountains,  and  left  them  on  the  ground  in  Ceylon.  Stone-gath- 
erers would  then  throw  lumps  of  clay  over  the  gems,  and  leave  them 
until  the  cows,  "  disappointed  at  not  finding  the  stones,  and  fretting  and 
fuming  with  rage,"  returned  to  the  sea,  when  their  human  rivals  would 
come  and  get  the  stones. 


97 


BERYL 

(EMERALD,   AQUAMARINE,   ETC.) 

This  mineral  species  includes  a  number  of  varieties  which  are  highly 
valued  as  gems.  These  are,  besides  beryl  itself,  the  gems  emerald, 
aquamarine,  and  golden  beryl.  Of  these,  emerald  is  dark-green  beryl, 
aquamarine  bluish-green,  or  greenish-blue  beryl,  and  golden  beryl, 
yellow  beryl.  .  Chrysoberyl  is  not  a  variety  of  beryl. 

While  these  varieties  of  beryl  all  differ  in  color,  they  are  the  same 
mineral,  and  are  practically  identical  in  composition,  hardness,  and  other 
properties.  In  composition,  they  are  a  silicate  of  aluminum  and  glucinum, 
the  percentages  being, for  normal  beryl:  67  per  cent  of  silica,  19  per  cent 
of  alumina,  and  14  per  cent  of  glucina. 

The  beautiful  green  color  of  the  emerald  is  probably  due  to  a  small 
quantity  of  chromium  which  it  usually  contains,  though  some  authori- 
ties believe  organic  matter  to  be  the  coloring  ingredient.  To  what 
substance  the  other  varieties  of  the  species  owe  their  color  is  not 
known. 

In  hardness  the  varieties  of  beryl  differ  little  from  quartz,  the  hard- 
ness being  7.5  to  8.  They  are  somewhat  inferior,  therefore,  to  such 
gems  as  topaz,  sapphire,  and  ruby  in  wearing  qualities,  although  hard 
enough  for  ordinary  purposes. 

The  specific  gravity  of  beryl  is  also  about  like  that  of  quartz, 
ranging  from  2.63  to  2.80.  It  is,  therefore,  relatively  light  as  com- 
pared with  other  gems.  Beryl  is  practically  infusible,  and  is  not  attacked 
by  acids. 

Beryl  crystallizes  in  the  hexagonal  system.  It  usually  occurs  as 
six-sided  prisms,  commonly  terminated  by  a  single  flat  plane,  but  some- 
times by  numerous  small  planes,  giving  a  rounded  effect,  and  occasion- 
ally by  pyramidal  planes,  which  cause  the  prism  to  taper  to  a  sharp 
point. 

The  crystals  sometimes  grow  to  enormous  size,  exceeding  those 
of  any  other  known  mineral.  Thus,  one  found  in  Grafton,  New  Hamp- 
shire, was  four  and  one-quarter  feet  in  length,  and  weighed  two  thou- 
sand nine  hundred  pounds.  Another  in  the  same  locality  is  estimated 
to  weigh  two  and  one-half  tons.  In  the  Museum  of  the  Boston  Society 


437 


I      Golden  Beryl  (Siberia). 
Blue  Beryl  (Siberia). 


BERYL. 

3  Blue  Bervl  'Albany,  Maine). 
4-        Aquamarine  (Conn.) 
'      Golden  Beryl  (Conn.) 


copymsHT  i»oi,  sr  ».  w.  MUMFOHO, 
lp          Aquamarine  (Ural  Mountains). 
"I   ^nit-raid  i"  matrix  (Ural  Mountains) 


or 
UN/VE 


Crystal  forms  of  beryl 


of  Natural  History,  and  in  the  United  States  National  Museum,  are 
exhibited  single  crystals  also  of  great  size.  That  in  Boston  is  three 
and  one-half  feet  long  by  three  feet  wide,  and  weighs  several  tons. 
That  in  the  National  Muse- 
um weighs  over  six  hundred 
pounds. 

None  of  these  crystals  is 
of  a  high  degree  of  purity  or 
transparency,  but  the  crystal 
planes,  at  least  of  the  prisms, 
are  well  developed. 

Beryl    crystals   have    no 
marked  cleavage,  except  a  slight  one  parallel  with  the  base.     Where 
broken,  the  surface  shows  conchoidal  fracture. 

The  mineral  is  quite  brittle.  Some  emeralds  even  have  the  annoy- 
ing habit  of  breaking  of  their  own  accord  soon  after  removal  from 
the  mine.  This  can  be  prevented  by  warming  them  gradually  before 
exposing  them  to  the  heat  of  the  sun,  or  other  sudden  heat. 

Beryl  and  its  varieties  are  dichroic ;  i.  e.,  the  stones  exhibit  different 
colors  when  viewed  in  different  directions.  This  dichroism  can  some- 
times be  observed  by  the  naked  eye,  but  better  with  the  dichroscope. 
With  this  instrument  the  twin  colors  seen  are,  for  the  emerald,  yellowish 
green  and  bluish-green;  for  the  aquamarine,  straw-white  and  gray- 
blue;  and  for  noble  beryl,  sea-green  and  azure.  The  dichroism  when 
seen  furnishes  a  positive  means  of  distinguishing  a  true  stone  from  any 
glass  imitations. 

The  varieties  of  beryl  have  not  the  brilliancy  of  the  diamond,  the 
double  refraction  being  weak  and  the  dispersion  small.  They  therefore 
depend  on  their  body  colors  and  their  luster  for  their  beauty  and  attrac- 
tiveness. Fortunately  they  usually  exhibit  these  qualities  as  well  by 
artificial  light  as  by  daylight. 

Ordinary  beryl  is  a  mineral  of  comparatively  common  occurrence, 
being  often  found  in  granitic  and  metamorphic  rocks,  although  that  of 
common  occurrence  is  usually  too 'clouded  and  fractured  to  be  of  use  for 
gem-cutting.  There  are  many  localities,  however,  where  beryls  of  gem 
quality  occur. 

Of  the  different  varieties  of  beryl,  the  emerald  is  by  far  the  most 
important  as  a  gem.  Its  pure  green  color,  unalloyed  by  a  single  ray 
of  yellow,  has  ever  made  it  an  object  to  be  sought  for  with  avidity, 
and  it  will  probably  always  be  the  standard  green  gem. 

The  finest  emeralds  in  the  world  come  from  Muso,  a  locality  in  the 


United  States  of  Colombia,  seventy-five  miles  north-northwest  of  Bogota. 
It  is  a  somewhat  inaccessible  region,  and  the  mining  of  the  gems  is 
a  precarious  occupation.  The  emeralds  occur  in  a  dark,  bituminous  lime- 
stone, which  is  shown  by  fossils  to  be  of  Cretaceous  age.  As  emeralds 
in  other  localities  occur  only  in  eruptive  or  metamorphic  rocks,  it  seems 
possible  that  the  Muso  emeralds  have  washed  in  from  an  older  forma- 
tion. The  emerald-bearing  beds  are  horizontal,  overlying  red  sandstone 
and  clay  slate.  Calcite,  quartz,  pyrite,  and  the  rare  mineral  parisite  are 
other  minerals  found  associated  with  the  emerald.  The  manner  of  work- 
ing these  emerald  mines  is  thus  described  by  Streeter : 

"The  mine  is  worked  by  a  company,  who  pay  an  annual  rent  for 
it  to  the  government,  and  employ  one  hundred  and  twenty  workmen. 
It  has  the  form  of  a  tunnel,  of  about  one  hundred  yards  deep,  with 
very  inclined  walls.  On  the  summit  of  the  mountains,  and  quite  near 
to  the  mouth  of  the  mine,  are  large  lakes,  whose  waters  are  shut 
off  by  means  of  water-gates,  which  can  be  easily  shifted  when  the 
laborers  require  water.  When  the  waters  are  freed  they  rush  with 
great  rapidity  down  the  walls  of  the  mine,  and  on  reaching  the  bottom 
of  it  they  are  conducted  by  means  of  an  underground  canal  through 
the  mountain  into  a  basin.  To  obtain  the  emeralds  the  workmen  begin 
by  cutting  steps  on  the  inclined  walls  of  the  mine,  in  order  to  make 
firm  resting-places  for  their  feet.  The  overseer  places  the  men  at  cer- 
tain distances  from  each  other  to  cut  out  wide  steps  with  the  help 
of  pickaxes.  The  loosened  stones  fall  by  their  own  weight  to  the 
bottom  of  the  mine.  When  this  begins  to  fill,  a  sign  is  given  to  let 
the  waters  loose,  which  rush  down  with  great  vehemence,  carrying  the 
fragments  of  rock  with  them  through  the  mountain  into  the  basin. 
This  operation  is  repeated  until  the  horizontal  beds  are  exposed  in 
which  the  emeralds  are  found." 

The  mines  are  owned  by  the  government,  by  whom  they  are  leased 
for  terms  of  seven  to  fifteen  years  to  the  highest  bidder.  The  working 
of  the  mines  has  been  almost  continuous  since  1558,  and  they  have  been 
the  principal  source  of  emeralds  obtained  in  modern  times.  Emeralds 
also  occur  in  small  numbers  throughout  the  black  aluminous  schists 
of  the  Eastern  Cordilleras  of  Colombia.  A  few  are  thus  obtained  from 
Cozenez,  Somondose,  Nemocon,  etc.  They  are  not  mined  systematically 
except  at  Cozenez. 

The  next  most  prominent  locality  whence  gem  emeralds  are  obtained 
is  in  Siberia,  on  the  river  Takovaya,  forty-five  miles  east  of  Ekaterinburg. 
The  emeralds  here  found  are  often  larger  than  any  yet  obtained  in 
South  America,  but  they  are  not  of  so  good  quality.  They  occur  in 

100 


mica  schist  (see  colored  plate),  and  often  associated  with  phenacite, 
chrysoberyl,  rutile,  etc. 

Other  localities  whence  emeralds  are  obtained  are  Upper  Egypt 
(the  source  of  those  known  to  the  ancients) ;  the  Heubachthal  in 
Austria;  and  Alexander  County,  North  Carolina,  in  our  own  country. 
The  latter  locality  has  afforded  a  number  of  fine  crystals,  and  work 
at  the  mines  has  recently  been  renewed. 

The  form  of  cutting  given  the  emerald  depends  upon  the  shape  of 
the  rough  stone.  The  table  cut  like  that  of  the  emerald  shown  in  the 
frontispiece  to  this  work  is  perhaps  the  most  common.  The  step  cut  is 
also  employed,  and  brilliants  and  rose  cuts  are  occasionally  made. 

Emeralds  seem  to  have  been  known  and  prized  from  the  earliest 
times.  They  are  mentioned  in  the  Bible  in  several  places,  and  their  use 
in  Egypt  dates  back  to  an  unrecorded  past,  for  they  frequently  appear 
in  the  ornaments  found  upon  mummies.  Readers  of  Roman  history 
will  remember  that  the  EmperoikNero  used  an  emerald  constantly  as  an 
eye-glass,  though  whether  this  was  a  real  emerald  may  be  questioned. 

The  Incas,  Aztecs,  and  other  highly  civilized  peoples  of  South  America 
were  reported  to  have  used  these  gems  profusely  for  purposes  of  adorn- 
ment and  for  votive-offerings.  It  was  partly  the  desire  to  secure  emeralds 
which  led  Cortez  and  his  followers,  early  in  the  sixteenth  century,  to 
undertake  the  conquest  of  Peru.  Some  of  the  emeralds  thus  obtained 
from  the  Incas  by  Cortez  and  brought  to  Spain  were  said  to  have 
been  marvels  of  the  lapidary's  art.  One  was  carved  into  the  form 
of  a  rose,  another  that  of  a  fish  with  golden  eyes,  and  another  that 
of  a  bell  with  a  pearl  for  a  clapper.  During  the  years  following  Cortez' 
conquest  large  quantities  of  the  so-called  emeralds  were  brought  to  Europe. 
Joseph  d'Acosta,  a  traveler  of  the  period,  says  the  ship  in  which  he 
returned  from  America  to  Spain  carried  two  chests,  each  of  which  con- 
tained one  hundred  pounds'  weight  of  fine  emeralds.  It  is  probably, 
however,  quite  incorrect  to  regard  the  stones  as  true  emeralds.  They 
were  more  likely  jade  or  some  other  green  stone  to  which  the  name 
emerald  was  applied.  The  true  emerald  is  too  brittle  to  be  easily  en- 
graved, and  it  is  not  likely  that  any  such  large  quantity  as  reported 
was  ever  found  of  this  stone.  Working  of  the  Colombian  mines  was 
begun  by  the  Spaniards  in  1558,  and  there  has  been  practically  no 
interruption  in  their  operation  since  that  time. 

The  ancients  had  many  superstitions  regarding  the  emerald,  one 
being  that  it  had  a  power  to  cure  diseases  of  the  eye.  Engravers  of  gems 
and  other  artificers  were  accustomed,  therefore,  to  keep  an  emerald  in 

front  of  them  while  at  work,  believing  it  would  rest  their  eyes  to  look 

101 


upon  it  occasionally,  and  that  the  water  in  which  the  stone  stood  would 
cure  inflammation  of  those  organs.  Another  notion  was  that  the  emerald 
would  reveal  the  inconstancy  of  lovers  by  changing  color. 

"It  is  a  gem  that  hath  the  power  to  show 
If  plighted  lovers  keep  their  troth  or  no; 
If  faithful,  it  is  like  the  leaves  of  spring; 
If  faithless,  like  those  leaves  when  withering." 

Another  belief  was  that  the  emerald  would  blind  the  eyes  of  the  ser- 
pent, a  fancy  referred  to  in  Moore's  lines : 

"Blinded  like  serpents  when  they  gaze 
Upon  the  emerald's  virgin  blaze." 

The  emerald  was  also  the  symbol  of  immortality  and  of  conquered 
sin  and  trial.  It  was  believed  that  emeralds  came  from  the  home  of  the 
griffin,  and  that  to  obtain  them  thence  exposed  the  miner  to  great  danger. 

As  late  as  the  seventeenth  century  powdered  emerald  was  widely 
used  as  a  drug,  being  regarded  when  taken  internally  as  a  powerful 
remedy  for  dysentery,  epilepsy,  venomous  bites,  and  fevers. 

Like  all  other  gems,  the  value  of  emeralds  varies  much  according 
to  their  perfection.  Those  of  the  best  grade  are  worth  from  $100  to 
$1,000  a  carat.  The  passion  for  emeralds  at  the  present  time,  together 
with  the  fact  that  very  few  are  being  found,  makes  them  among  the 
most  costly  of  gems.  A  three-carat  emerald  recently  sold  for  $875, 
and  a  six-carat  stone  for  $4,000.  A  six-carat  diamond  might  not  be 
worth  over  $1,000  at  present.  The  color  should  be  a  dark  velvety 
green,  those  of  lighter  shades  being  much  less  valuable.  Owing  to  the 
extreme  brittleness  of  the  mineral,  emeralds  usually  contain  flaws,  so 
that  "  an  emerald  without  a  flaw  "  has  passed  into  a  proverb  to  indicate 
a  thing  almost  unattainable. 

The  largest  and  most  beautiful  emerald  known  to  be  in  existence 
at  the  present  time  is  one  owned  by  the  Duke  of  Devonshire.  This 
is  an  uncut,  six-sided  crystal,  about  two  inches  long,  and  of  the  same 
diameter.  It  is  of  perfect  color,  almost  flawless,  and  quite  transparent. 

Aquamarines  and  other  beryls  are  found  in  Siberia,  India,  Brazil, 
and  in  many  localities  in  the  United  States.  Pieces  suitable  for  cutting 
are  quite  frequently  found,  and  the  cut  stones  are  much  lower  in  price 
tnan  the  emerald.  Large  stones  are  frequently  obtained.  Dana  mentions 
an  aquamarine  from  Brazil  which  approaches  in  size,  and  also  in  form, 
the  head  of  a  calf.  It  weighs  225  ounces  troy,  is  transparent,  and 
without  a  flaw.  In  the  Field  Columbian  Museum  is  to  be  seen  a  beau- 
tiful cut  aquamarine  from  Siberia  more  than  two  inches  in  diameter, 

102 


which  weighs  331  carats.  Here  is  also  the  finest  specimen  of  blue 
beryl  ever  cut  in  the  United  States.  It  was  found  in  Stoneham,  Maine, 
is  rich  sea-green  color  in  one  direction  and  sea-blue  in  another.  It 
weighs  133  carats.  Numerous  other  Maine  localities  have  furnished 
gem  beryls.  Golden  beryls  are  found  in  Maine,  Connecticut,  North  Caro- 
lina, Pennsylvania,  and  other  United  States  localities,  as  well  as  in  Siberia 
and  Ceylon.  From  them  are  obtained  gems  of  rich  golden  color  resem- 
bling topaz  or  citrine. 

Beryl  of  a  pale  rose  color  is  sometimes  found,  and  when  of  good 
quality  is  cut  for  gem  purposes,  but  it  is  of  too  rare  occurrence  to  be 
important.  A  variety  of  beryl  containing  two  to  three  per  cent  of  the 
metal  caesium  is  found  at  Hebron,  Maine,  which  affords  transparent, 
colorless  stones  of  a  brilliant  luster. 

Aquamarine  and  other  varieties  of  beryl  seem  not  to  have  been 
as  highly  esteemed  as  emerald  by  the  ancients,  although  beryl  is  men- 
tioned in  the  Bible,  and  early  writers  describe  gems  evidently  belong- 
ing to  the  species.  A  notable  biblical  mention  is  that  found  in  the 
Song  of  Solomon,  where  it  is  said: 

"0  daughters  of  Jerusalem, 
This  is  my  beloved  and  this  is  my  friend, 
His  hands  are  as  gold  rings  set  with  the  beryl." 

The  beryl  was  believed,  in  the  Middle  Ages,  to  give  its  wearer  insight, 
second  sight,  and  foresight,  to  induce  sleep  and  compose  the  heart  and 
mind.  It  was  called  "  the  sweet-tempered  stone."  It  was  especially 
used  in  the  seventeenth  century  for  divination,  the  method  being  to 
suspend  a  ring  containing  a  beryl  in  a  bowl  filled  with  water.  The  edges 
of  the  bowl  being  marked  with  the  letters  of  the  alphabet,  the  beryl  gave 
answers  to  questions  asked  by  stopping  before  certain  letters.  It  was 
also  supposed  to  possess  special  power  over  evil  spirits,  and  it  was  said 
that  a  man  might  call  a  devil  out  of  hell  and  receive  answers  to  such 
questions  as  he  might  ask  if  he  but  held  a  beryl  in  his  mouth.  The 
globe  in  the  English  crown  is  surmounted  by  a  blue  beryl,  in  allusion 
perhaps  to  the  supposed  magical  power  of  the  stone. 


103 


EUCLASE 

Euclase  is  a  rare  mineral,  resembling  beryl  in  color  and  hardness, 
and  like  it  a  silicate  of  glucina  and  alumina.  It  differs  from  beryl, 
however,  in  containing  water  in  its  composition,  in  being  monoclinic 
in  crystallization,  and  in  having  higher  specific  gravity.  The  percen- 
tage composition  of  euclase  is:  Silica  41.3,  alumina  35.2,  glucina  17.3, 
and  water  6.2.  Its  specific  gravity  is  3.05-3.10.  It  barely  fuses  before 
the  blowpipe,  and  is  not  attacked  by  acids.  It  has  a  vitreous  luster, 
which  becomes  more  brilliant  on  polishing  a  surface.  The  cut  stones 
are  made  from  transparent  crystals,  which  range  from  colorless  to  blue 
and  green,  the  latter  resembling  Russian  topaz  and  aquamarine.  Brazil 
and  the  Ural  Mountains  furnish  practically  all  the  euclase  thus  far 
known,  and  this  in  but  small  quantity.  The  Brazilian  euclase  is  found 
at  Boa  Vista,  in  the  province  of  Minas  Geraes,  in  the  same  locality 
with  yellow  topaz.  It  occurs  in  nests  in  quartz  veins  which  penetrate 
the  schists  of  the  region.  The  crystals  found  in  the  Urals  are  larger, 
one  three  inches  in  length  being  known.  ^Euclase  is  also  found  in  the 
auriferous  gravels  of  the  Sanarka  River  in  the  Government  of  Orenburg, 
Russia,  chrysoberyl  and  topaz  being  accompanying  minerals.  Euclase 
possesses  a  strong  cleavage,  which  gives  it  its  name,  and  makes  it  some- 
what difficult  to  cut.  On  account  of  the  rarity  of  the  mineral  good 
stones  command  a  high  price. 


PHENACITE 

Phenacite  affords  transparent,  colorless  gems  of  a  brilliant  vitreous 
luster.  They  are  usually  cut  as  brilliants,  and  stand  between  the  dia- 
mond on  the  one  hand  and  rock  crystal  on  the  other  in  the  amount  of 
ufire"  they  display.  Phenacite  has  stronger  double  refraction  than 
quartz,  and  a  higher  index  of  refraction.  It  is  far,  however,  from 
equaling  the  diamond  in  these  properties.  In  fact,  it  resembles  quartz 
so  much  that  it  was  not  until  1833  recognized  as  a  distinct  species. 
The  name  of  phenacite,  from  the  Greek  phenax,  a  deceiver,  was  given 
to  it  because  of  this  resemblance.  Like  beryl  and  euclase,  pheuacite 
is  a  silicate  of  glucinum.  Its  percentage  composition  is,  silica  54.45, 
glucina  45.55.  It  is  infusible  before  the  blowpipe,  and  can  be  distin- 
guished chemically  from  quartz  by  putting  a  drop  of  cobalt  nitrate  on  a 
heated  fragment  and  then  reheating.  The  fragment  turns  blue  if  phena- 
cite ;  if  quartz  it  remains  black.  Phenacite  is  harder  and  slightly  heavier 
than  quartz,  its  hardness  being  7.5-8,  and  its  specific  gravity  2.97-3.  It 
crystallizes  in  the  rhombohedral  division  of  the  hexagonal  system.  The 
gems  are  usually  obtained  from  crystals. 

Phenacite  is  not  a  common  mineral,  and  nearly  all  that  has  been  cut 
for  gems  has  come  from  two  localities,  '^Takovaya,  near  Ekaterinburg, 
Russia,  and  Mt.  Antero,  Chaffee  County,  Colorado.  The  first  locality 
furnishes  the  finest  and  largest  stones,  some  of  them  weighing  thirty  to 
forty  carats.  They  occur  together  with  emerald  and  chrysoberyl  in 
mica  schist.  The  Mt.  Antero  phenacite  is  found  at  an  elevation  of  14,000 
feet,  and  is  obtainable  for  only  a  short  period  during  the  summer  on 
account  of  the  abundant  snows  of  the  region.  This  locality  affords 
smaller  gems  than  the  Russian,  and  owing  to  the  demand  for  them  as 
mineralogical  specimens,  few  are  cut.  They  usually  occur  implanted 
on  quartz,  beryl,  or  feldspar.  Some  good  phenacite  has  been  found 
on  Bald  Mountain,  near  North  Chatham,  New  Hampshire,  in  a  granite 
vein  and  near  Florissant,  Colorado.  Besides  being  colorless,  phenacite 
may  exhibit  pale  rose  and  wine-yellow  colors. 


105 


CHRYSOBERYL 

This  mineral  is  like  beryl  in  containing  the  element  glucinum 
(beryllium),  but  in  other  respects  is  a  distinct  species.  Chrysoberyl  has 
no  silica  in  its  composition,  as  has  beryl,  but  is  composed  of  glucina 
and  alumina,  the  theoretical  percentages  being  glucina  19.8,  alumina 
80.2.  In  nature,  however,  some  other  oxides  are  usually  present  as 
impurities  or  replacing  the  alumina.  Such  are  iron  and  chromium 
oxides.  Chrysoberyl  is  remarkable  for  its  hardness,  this  being  8.5,  and 
thus  near  that  of  corundum.  The  cut  stones  therefore  retain  a  polish 
well.  The  specific  gravity  of  the  mineral  is  somewhat  greater  than  that 
of  the  diamond,  being  3.5  to  3.8.  It  crystallizes  in  the  orthorhombic 
system,  and  often  forms  twins  which  are  so  united  as  to  make  a  six- 
rayed  stellate  crystal,  or  six-sided  prisms.  An  illustration  of  one  of  these 
crystals  may  be  seen  in  the  colored  plate.  Chrysoberyl  has  a  prismatic 
cleavage  and  conchoidal  fracture.  Its  luster  is  vitreous,  tending  to  oily, 
and  is  brilliant.  The  mineral  is  infusible,  and  is  not  attacked  by  acids. 
In  color  it  usually  presents  some  shade  of  green,  tending  at  times  to 
brown  or  yellow.  The  name  chrysoberyl  means  literally  golden  beryl, 
and  suggests  a  yellow  stone.  While  this  is  a  common  color,  grass-green 
and  erne  raid -green  are  frequent  and  characteristic.  Among  jewelers 
chrysoberyl,  especially  the  Brazilian  chrysoberyl,  is  often  known  as 
chrysolite,  a  custom  which  has  doubtless  arisen  through  the  similarity 
in  color  of  the  two  minerals.  Three  kinds  of  chrysoberyl  are  employed 
in  jewelry,  and  being  given  different  names  may  be  considered  separately. 
These  are :  (1)  ordinary  chrysoberyl,  (2)  cymophane,  or  cat's-eye,  and  (3) 
alexandrite.  Ordinary  chrysoberyl,  also  called  Oriental  chrysolite,  or 
chrysolite,  is  greenish-yellow  to  smoky-brown  in  color,  and  is  employed 
as  a  gem  only  when  transparent.  It  is  for  the  most  part  obtained  in 
Brazil  and  Ceylon,  in  the  gem  gravels  of  both  of  which  countries  it  occurs. 
The  Brazilian  chrysoberyls  are  rolled  pebbles,  scarcely  larger  than  beans, 
and  occur  together  with  topaz,  garnet,  tourmaline,  quartz,  etc.,  in  the  beds 
of  streams  chiefly  in  the  northern  part  of  the  province  of  Minas  Geraes. 
The  stones  occur  in  the  neighborhood  of  granite  and  gneiss,  and  were 
therefore  probably  originally  formed  in  these  rocks.  The  (Ceylonese 
chrysoberyls  are  likewise  found  in  stream  beds,  and  come  from  Sa^ra- 

106 


gam  and  the  neighborhood  of  Matura  in  the  southern  part  of  the  island. 
In  North  America,  chrysoberyl  has  been  found  in  Maine,  Connecticut,  and 
North  Carolina,  but  few  stones  sufficiently  transparent  for  cutting  occur. 
Cymophane,  or  "cat's-eye,"  is  a  name  given  to  a  translucent,  opalescent 
variety  of  chrysoberyl,  across  a  polished  surface  of  which  may  be  seen 
to  play  a  single  long,  narrow  ray  of  light,  changing  position  with  every 
movement  of  the  stone.  The  phenomenon  is  like  that  exhibited  by  star 
sapphires,  except  tiiat  but  a  single  ray  is  seen  instead  of  several.  The 
cause  of  the  appearance  is  believed  to  be  multitudes  of  minute  tube-like 
cavities  in  the  stone  arranged  in  parallel  position,  which  reflect  the  light 
which  falls  upon  them.  In  cutting  the  stone  the  best  effect  is  produced 
by  giving  it  the  form  of  a  long  oval,  over  the  middle  of  which  a  light 
ray  runs  and  produces  a  resemblance  to  the  eye  of  a  cat.  Such  stones 
are  the  true  "cat's-eyes"  of  jewelry,  the  quartz  cat's-eye  being  much 
inferior.  The  name  cymophane,  also  applied  to  these  stones,  comes  from 
two  Greek  words,  meaning  wavy  appearance.  The  cat's-eye  variety  of 
chrysoberyl  occurs  together  with  the  transparent  kind  above  described 
in  the  alluvial  deposits  of  Ceylon  and  Brazil.  The  stones  are  not  large, 
rarely  exceeding  100  carats  in  weight.  The  largest  and  finest  known  is 
in  the  South  Kensington  Museum  of  England,  and  is  about  an  inch  and 
a  half  in  length  and  of  the  same  thickness. 

In  Oriental  countries  the  cat's-eye  has  long  been  highly  esteemed  a 
preserver  of  good  fortune,  the  belief  being  that  each  stone  is  inhabited 
Iby  a  good  spirit.  It  is  believed  to  be  a  guardian  of  its  owner's  wealth 
and  to  protect  him  from  poverty.  The  stone  is  often  carved  by  Orientals 
into  the  form  of  some  animal's  head,  thus  increasing  its  weird  and 
mysterious  aspect.  The  popularity  of  the  stone  among  Europeans  was 
suddenly  increased  a  few  years  ago  when  the^Duke  of  Connaught  gave 
one  in  a  betrothal  ring  to  his  bride,  Princess  Margaret  of  Prussia.  Cat's- 
eye  immediately  became  the  fashion  among  the  wealthy  classes,  and  the 
supply  proved  quite  unequal  to  the  demand.  The  stone  is  still  quite 
fashionable,  and  not  less  than  one  hundred  dollars  per  carat  must  often 
be  paid  to  secure  a  good  one. 

Alexandrite  is  a  variety  of  chrysoberyl  found  in  the  Ural  Mountains, 
and  received  its  name  from  the  fact  that  it  was  first  found  on  the  birth- 
day of  Alexander  II.,  Czar  of  Russia,  in  the  year  1830.  Moreover,  the 
colors  which  it  presents,  green  and  red,  are  the  national  colors  of  Russia. 
Alexandrite  by  ordinary  light  is  dark  grass-green,  or  emerald-green,  in 
color,  but  on  holding  it  to  the  sunlight,  or  viewing  it  by  artificial  light, 
it  appears  columbine-red.  The  gem  has  therefore  the  unique  property 
of  appearing  as  "an  emerald  by  day  and  amethyst  by  night."  The 

107 


locality  where  alexandrite  was  originally  found,  and  where  most  of  it 
has  been  obtained,  is  ^akovaya,  near  Ekaterinburg.  Only  the  trans- 
parent pieces  can  be  used  for  gems,  and  as  these  are  relatively  scarce, 
the  price  of  the  gem  is  high.  Of  late  alexandrite  has  been  found  in 
the  gold  sands  of  Sanurka  in  the  southern  Urals,  but  a  more  impor- 
tant source  of  supply  has  appeared  in  Ceylon,  where  gems  much 
larger  than  those  in  the  Urals,  and  in  a  fine  variety  of  colors,  have 
been  found. 


108 


ZIRCOtf 

Zircon  is  a  mineral  remarkable  among  those  employed  as  gems  for  its 
high  specific  gravity  and  adamantine  luster.  For  these  reasons  the  color- 
less, transparent  stones  are  sometimes  employed  as  substitutes  for  the  dia- 
mond, although  they  lack  the  high  refractive  power  and  hence  play  of  colors 
of  the  latter.  The  stones  are  sometimes  called  "Matura  diamonds," 
because  of  their  abundance  at  Matura  in  the  island  of  Ceylon.  The  color- 
less, or  smoky  zircons,  are  often  known  as  "  jargons  "  or  "  jargoons," 
a  name  said  to  have  been  given  in  allusion  to  the  fact  that  though 
they  resembled  the  diamond  in  luster  they  had  really  much  less 
value.  Besides  zircons  of  this  sort  there  are  those  known  in  jewelry 
as  "  hyacinth  "  or  "  jacinth,"  which  are  transparent  zircons  of  a  brown- 
ish, red-orange  color.  A  stone  of  a  nearly  similar  color  is  furnished 
by  the  essonite  variety  of  garnet,  and  this  is  also  often  known  as 
hyacinth. 

The  high  specific  gravity  of  zircon  above  referred  to  is  more  than 
four  times  the  weight  of  water,  determinations  giving  results  varying 
between  4.2  and  4.86.  Zircon  is  thus  the  heaviest  of  gems,  and  will 
sink  at  once  in  any  of  the  ordinary  heavy  liquids.  The  hardness 
of  zircon  is  between  that  of  quartz  and  topaz,  being  7£.  Its  index 
of  refraction  is  high,  being  1.92,  or  near  to  the  diamond  among  gems, 
a  fact  which  accounts  for  its  brilliancy  when  cut.  Before  the  blowpipe 
zircon  is  infusible.  It  is  not  acted  upon  by  acids  except  in  fine  powder 
by  sulphuric  acid.  In  composition  it  is  a  silicate  of  zirconium,  the  per- 
centages being  silica  32.8,  zirconia  67.2.  It  usually  also  contains  a  little 
iron  oxide.  It  is  not  an  uncommon  mineral  in  rocks,  occurring  in 
crystals  of  microscopic  size,  and  in  crystalline  rocks  it  sometimes 
occurs  in  large  and  abundant  crystals.  These  are  usually  opaque  and 
of  no  value  for  gem  purposes,  although  they  are  mined  to  some  extent  at 
the  present  time  for  use  in  incandescent  lights.  Opaque  zircon  is  found 
in  this  country  in  Georgia,  Colorado,  New  York,  and  Canada.  The 
form  of  the  crystals  is  usually  that  of  four-sided  prisms  terminated 
by  pyramids.  The  transparent  zircons  available  for  gems,  that  is,  the 
so-called  "  noble  "  zircons,  come  almost  wholly  from  the  island  of  Ceylon, 
where  they  occur  in  the  gem  gravels  that  contain  also  rubies,  sapphires, 

109 


garnets,  tourmalines,  etc.  The  zircons  are  in  the  form  of  rolled  pebbles, 
rarely  of  large  size,  few  stones  of  over  ten  or  twelve  carats  weight 
being  found.  In  other  localities  some  noble  zircons  are  found  in  pan- 
ning for  gold,  the  high  specific  gravity  of  the  zircon  causing  it  to  stay 
in  the  pans  almost  as  long  as  the  gold.  Along  the  Espailly  River, 
in  Auvergne,  France,  are  found  zircons  which  yield  brilliant  though 
small  stones  of  the  true  jacinth  color.  Neither  in  the  form  of  hyacinth, 
or  jargoon,  is  zircon  at  the  present  time  very  extensively  used  in  jewelry, 
although  it  has  many  of  the  qualities  desirable  for  gems.  The  best 
stones  are  rarely  valued  now  at  more  than  ten  dollars  per  carat, 
although  they  were  once  highly  prized.  One  peculiarity  of  zircon 

that  should  be  noted 
is  the  change  of  its 
color  which  some- 
times takes  place  on 
long  exposure  to 
light,  the  color 
sometimes  thus  dis- 
appearing altogeth- 
er. It  is  usually, 
also,  driven  out  by 
heating.  As  it  has 
been  found  that  the  mineral  when  heated  away  from  oxygen  does  not 
lose  or  change  its  color,  the  conclusion  is  drawn  by  some  that  the 
color  depends  on  the  state  of  oxidation  of  contained  iron;  but  others 
think  it  of  organic  origin.  The  red  varieties  of  zircon  are  sometimes 
sold  for  rubies,  but  they  may  be  easily  distinguished  from  true  rubies  by 
their  lower  hardness  and  higher  specific  gravity.  Zircon  becomes  phos- 
phorescent but  not  electric  upon  heating. 

The  ancients  employed  a  stone  which  they  knew  as  hyacinth;  but 
its  color  was  bluish,  and  hence  it  is  generally  supposed  to  have  been 
our  sapphire  or  amethyst.  The  lyncurion  of  Theophrastus  is  more  likely 
to  have  been  our  zircon,  the  ancients  having  employed  it  for  making 
signets,  some  of  which  are  still  preserved.  In  the  Middle  Ages  hyacinth 
was  supposed  to  have  the  power  of  procuring  sleep,  riches,  honor,  and 
wisdom,  and  of  driving  away  plagues  and  evil  spirits.  Cardanus,  writing 
in  the  sixteenth  century,  says  that  he  was  accustomed  to  carry  a  hya- 
cinth (jacinth)  about  with  him  for  the  purpose  of  inducing  sleep,  which 
"  it  did  seem  somewhat  to  confer,  but  not  much." 


Forms  of  zircon  crystals 


110 


429 


Green  Tourmaline  (Brazil). 

Green  Tourmaline  (Haddam,  Conn.) 

Cross  Section  of  Green  Tourmaline  (Cal.) 


TOURMALINE. 
Red  Tourmaline  or  Rubellite  (Island  of  Elba). 

Brown  Tourmaline  (Gouverneur,  K.  Yj 
Red  Tourmaline  or  RuUellite,  in  Lepidolite  (Cal.) 


COPymiMT    1(03,  IV  A.  W.  MUMFOHO,  CHNMO. 

Black  Tourmaline  (Finland). 


TOURMALINE 

Early  in  the  eighteenth  century  some  children  of  Holland,  playing 
on  a  warm  summer's  day  in  a  courtyard  with  a  few  bright  colored 
stones,  noticed  that  these  possessed  a  strange  power  when  warmed  by 
the  heat  of  the  sun.  They  attracted  and  held  ashes  and  straws.  On 
reporting  this  strange  discovery  to  their  parents  the  latter,  it  is  said, 
could  give  no  explanation  of  the  curious  property,  but  left  a  record 
of  their  knowledge  of  it  in  the  name  of  " aschentreckers,"  or  "ash- 
drawers,"  which  they  gave  the  stones,  and  by  which  they  were  known 
for  a  long  time. 

This  was  the  method  of  introduction  to  the  civilized  world  of  the 
mineral  now  known  as  tourmaline,  a  mineral  which  in  variety  of  color, 
composition,  and  properties  is  of  considerable  interest  in  Nature. 

The  lapidaries  who  had  given  the  Dutch  children  the  stones  for  play- 
things did  not  recognize  them  as  different  from  the  other  gems  with  which 
they  were  accustomed  to  deal.  So  to  the  present  day,  although  tour- 
maline is  considerably  used  in  jewelry,  it  is  rarely  ever  called  by  that 
name.  The  green  varieties  are  often  known  as  Brazilian  emerald,  chrys- 
olite, or  peridot,  some  varieties  of  blue  as  Brazilian  sapphire,  others  as 
indicolite,  the  colorless  as  achroite,  and  the  red  as  rubellite,  siberite,  and 
even  as  ruby. 

It  is  only  somewhat  recently  that  these  different  stones  have  been 
recognized  as  being  varieties  of  a  single  mineral  species  which  is  known 
by  the  name  tourmaline.  This  name  comes  from  a  Cingalese  word 
(turamali),  which  was  applied  to  the  first  tourmaline  gems  sent  from 
Ceylon  to  Holland. 

At  one  time  the  name  schorl  was  chiefly  applied  to  the  species.  This 
was  before  the  means  of  distinguishing  mineral  species  were  as  well 
understood  as  they  are  now,  and  a  large  number  of  minerals,  and  even 
rocks,  were  included  under  the  name  schorl.  One  by  one,  however,  they 
were  distinguished  by  separate  names  until  schorl  included  only  tourma- 
line, and  shortly  afterward  the  name  schorl  was  dropped  altogether. 

In  its  opaque  form,  colored  either  black  or  brown,  tourmaline  is  a 
comparatively  common  mineral.  It  accompanies  many  so-called  meta- 
morphic  rocks,  and  is  also  common  in  granite  and  other  eruptive  rocks. 

ill 


As  a  rock-forming  mineral  it  often  occurs  as  long,  slender  prisms,  fre- 
quently about  the  size  of  a  darning-needle,  and  radiating  in  all  directions. 
The  only  mineral  for  which  it  is  likely  to  be  mistaken  in  this  form  is 
hornblende.  It  can  be  distinguished  from  this  in  the  following  manner  : 
On  fusing  the  powdered  mineral  with  a  mixture  of  bisulphate  of  potash 
and  fluor-spar  (best  done  on  a  little  loop  of  platinum  wire)  tourmaline 
will  color  the  flame  green,  while  hornblende  will  produce  no  coloration. 

The  black  opaque  crystals  of  tourmaline  often  reach  a  large  size,  some 
being  known  four  feet  in  length.  Both  black  and  brown  tourmaline  are 
usually  opaque,  and  hence  have  no  value  as  gems.  Tourmaline  of  other 
colors,  however,  is  often  transparent,  and  this  is  of  gem  value. 

The  gem  tourmalines  are  to  be  found  in  only  a  few  localities.  They 
occur  in  Maine,  Connecticut,  and  California  in  our  own  country,  and 
also  in  Brazil,  Russia,  and  Ceylon.  The  crystals  are  usually  in  the 
form  of  long,  slender  prisms,  often  having  the  peculiarity  of  being  differ- 
ently colored  in  different  portions.  Thus  a  crystal  may  be  green  at 
one  end  and  red  at  the  other,  and  in  cross-section  may  show  a  blue 
center,  then  a  colorless  zone,  then  one  of  red,  and  then  one  of  green. 
Some  of  the  crystals  from  Paris,  Maine,  change  from  white  at  one  termi- 
nation to  emerald  green,  then  light  green,  then  pink,  and  finally  are 
colorless  at  the  other  termination.  In  some  crystals  again  the  red  passes 
to  blue,  the  blue  to  green,  and  the  green  to  black. 

Exactly  what  produces  these  differences  of  color  is  not  known.  It  is 
known  that  black  tourmaline  has  an  excess  of  iron,  the  red  and  green  an 
excess  of  sodium  and  lithium,  and  the  yellow  and  brown  an  excess  of 
magnesium  in  their  composition.  These  same  differences  of  composition 
characterize  similar  colors  in  portions  of  the  same  crystal  as  well  as 
separate  crystals.  Hence  the  evidence  is  quite  conclusive  that  the  color 
in  some  way  depends  on  the  composition.  Many  transparent  tourma- 
lines, while  appearing  of  a  uniform  color  when  viewed  in  any  one 
direction,  exhibit  different  colors  when  viewed  in  different  directions. 
Thus,  one  of  the  long,  slender  crystals  may  appear  green  when  held 
lengthwise  in  front  of  the  eye,  but  when  looked  at  from  the  end  appears 
brown.  Again,  some  crystals  appear  perfectly  transparent  when  viewed 
perpendicularly  to  the  sides  of  the  prism,  but  when  viewed  from  the  end 
are  nearly  opaque.  This  may  be  true  even  when  the  thickness  is  less 
in  the  latter  direction.  Both  these  properties  are  due  to  the  arrange- 
ment of  the  molecules  of  tourmaline,  which  is  such  as  to  make  the  power 
of  absorbing  light  different  in  different  directions. 

The  form  of  crystals  of  tourmaline  is  usually  that  of  a  three-sided 
prism.  The  sides  of  the  prism  are  usually  marked  by  narrow  parallel 

112 


lines  called  striae,  and  the  prism  may  be  more  or  less  rounded  by  the 
addition  of  other  planes. 

If  a  doubly  terminated  crystal  be  examined  carefully,  it  will  be 
seen  that  the  planes  on  the  two  ends  are  not  alike,  either  in  number  or 
inclination.  On  one  end  there  may  be  three  planes,  on  the  other  six, 
or  even  twelve.  If  the  planes  on  one  end  make  a  blunt  termination, 
those  on  the  other  may  make  a  sharply  pointed  one.  Such  a  peculiarity 
of  crystal  form  is  possessed  by  but  few  minerals.  Those  possessing  it 
are  said  to  be  hemimorphic,  i.  e.,  half  formed.  Some  minerals,  among 
which  is  tourmaline,  which  exhibit  this  peculiarity  of  form  are  often 
also  pyroelectric,  i.  e.,  become  electric  on  heating.  It  was  this  devel- 
opment of  electricity  which  caused  the  stones  with  which  the  Dutch 
children  played,  to  pick  up  ashes,  etc.,  when  the  stones  were  warmed 
by  the  heat  of  the  sun.  Any  one  can  repeat  their  observation  by 
gently  heating  crystals,  or  even  fragments  of  tourmaline,  and  applying 
them  to  bits  of  paper.  The  electrical  attraction  will  often  be  found  to 
be  very  strong,  though  it  varies  with  different  crystals.  The  fragments 
should  not  be  overheated,  the  electricity  being  most  strongly  developed 
between  100°  and  200°  Fahrenheit. 

In  composition  tourmaline  is  a  complex  silicate,  chiefly  of  aluminum 
.  and  boron.  Iron,  magnesium,  the  alkalies,  and  water  also  enter  in  vary- 
ing amounts  into  it.  In  fact,  so  complicated  is  its  chemical  nature  that 
perhaps  no  other  mineral  has  been  so  often  analyzed  or  had  its  analyses 
so  much  discussed. 

Ruskin,  in  his  "Ethics  of  the  Dust,"  thus  describes  the  composition 
of  tourmaline :  "A  little  of  everything;  there's  always  flint  and  clay  and 
magnesia  in  it ;  and  the  black  is  iron  according  to  its  fancy;  and  there's 
boracic  acid,  if  you  know  what  that  is,  and  if  you  don't,  I  cannot  tell  you 
to-day,  and  it  doesn't  signify ;  and  there's  potash  and  soda ;  and  on  the 
whole,  the  chemistry  of  it  is  more  like  a  mediaeval  doctor's  prescription 
than  the  making  of  a  respectable  mineral." 

Tourmaline  is  both  harder  and  heavier  than  quartz,  its  hardness 
being  7-7.5,  and  its  specific  gravity  2.98-3.20.  It  is  thus  sufficiently 
hard  for  use  as  a  gem.  It  is,  however,  quite  brittle,  and  even  at  times 
friable.  Cracks  therefore  frequently  cut  across  good  crystals,  and  spoil 
what  would  otherwise  make  a  good  gem.  It  is  very  common  to  find 
tourmalines  in  the  rocks  broken  into  a  number  of  pieces,  and  the  frag- 
ments "mended "  together  with  quartz  or  calcite.  This  has  been  true  of 
the  black  tourmaline  shown  in  the  accompanying  plate.  Scarcely  any  other 
mineral  exhibits  this  change  so  often  as  tourmaline,  a  result  due  probably 
to  its  brittleness  and  the  character  of  the  rock  in  which  it  occurs. 

113 


The  strong  dichroism  of  tourmaline  should  be  borne  in  mind  in  cut- 
ting gems  from  it.  Since  a  crystal  looked  at  in  the  direction  of  the 
vertical  axis  is  usually  much  less  transparent  and  of  less  pleasing  color 
than  when  seen  at  right  angles  to  this  direction,  gems  should  be  cut  with 
the  table  parallel  to  the  prism.  They  will  then  exhibit  their  most  pleas- 
ing color  in  the  direction  in  which  they  are  usually  seen. 

Of  the  different  colors  of  tourmaline  used  for  gems,  red  shades  are 
less  abundant,  and  more  highly  prized  than  green.  Of  the  red  tourma- 
lines, those  dark  red  are  most  valued,  especially  if,  as  is  sometimes  the  case, 
a  color  like  that  of  the  ruby  is  exhibited.  A  rose-red  color  is,  however, 
more  common.  The  green  tourmalines  are  usually  dark  green,  shading 
to  blue  or  yellow,  and  almost  never  exhibit  the  true  emerald-green.  Blue 
tourmalines  are  least  abundant  of  any,  and  are  rarely  cut.  Their  color  is 
usually  an  indigo-blue.  Tourmaline  is  not  attacked  by  acids,  and  the 
transparent  varieties  are  infusible.  Partly  on  account  of  its  lack  of 
strong  color,  and  partly  because  it  is  not  better  known,  tourmaline  has 
not  hitherto  obtained  much  popularity  as  a  gem,  although  its  hardness, 
dichroism,  and  transparency  are  such  as  to  warrant  its  more  extensive  use. 

Recently,  however,  it  has  obtained  more  favor,  and  the  supply  of 
Brazilian  tourmalines  especially  is  hardly  equal  to  the  demand. 

One  of  the  best  known  localities  for  gem  tourmalines  is  Paris,  Maine. 
It  was  discovered  by  two  boys,  by  name  Elijah  L.  Hamlin  and  Ezekiel 
Holmes.  They  were  interested  in  the  study  of  minerals,  and  spent  much 
of  their  leisure  time  searching  for  them.  One  day  in  the  fall  of  1820, 
having  been  out  many  hours  hunting  for  minerals,  they  were  about  to 
return  home  when  a  gleam  of  something  green  at  the  roots  of  a  tree 
caught  their  eye.  Eagerly  bringing  it  to  light,  they  found  it  to  be  a 
beautiful  green  tourmaline.  A  fall  of  snow  that  night  prevented  their 
obtaining  more  of  the  crystals,  but  the  following  spring  they  returned 
and  secured  many  fine  gems.  The  locality  has  been  extensively  worked 
since  then,  and  has  furnished  many  fine  gems,  which  have  gone  to  adorn 
the  coronets  of  kings  and  enriched  the  mineral  cabinets  of  the  world. 
The  tourmaline  occurs  in  pockets  in  pegmatitic  granite.  Black  tour- 
maline, muscovite,  and  lepidolite  are  of  constant  occurrence  through  the 
granite.  The  granite  is  overlaid  by  mica  schist,  which  at  present  is 
being  stripped  off  to  permit  of  further  mining.  It  is  estimated  that  fifty 
thousand  dollars'  worth  of  tourmalines  have  been  taken  from  this  one 
locality.  Auburn  and  Rumford,  Maine,  are  two  other  neighboring  locali- 
ties where  good  gems  have  been  found.  At  Haddam  Neck,  Connecticut, 
fine  transparent  tourmalines  occur,  generally  green  in  color,  and  many 
of  them  of  gem  quality.  They  occur  in  granite. 

114 


Tourmaline  mine,  Mt.  Mica,  Paris,  Maine 


Tourmaline  mine,  Haddam,  Conn. 
115 


The  red  tourmaline  (rubellite)  from  California,  illustrated  in  the 
accompanying  colored  plate,  is  found  in  San  Diego  County  of  that  State. 
The  matrix  in  which  it  occurs  is  a  lithia-bearing  mica  ( lepidolite  )  of  a 
delicate  violet  color.  In  this  matrix  the  tourmaline  usually  occurs  in 
radiating  masses.  The  rose  color  of  the  tourmaline  contrasting  with 
the  violet  of  the  lepidolite  makes  an  object  which  is  quite  a  favorite 
with  mineral  fanciers,  although  the  former  is  not  sufficiently  transparent 
to  be  used  as  a  gem.  At  two  other  localities  in  the  same  State  large 
transparent  tourmalines  of  varying  colors  have  been  found. 

Tourmaline  is  found  frequently  in  Brazil  in  the  gem  gravels,  accom- 
panying topaz,  amethyst,  diamond,  etc.  It  is  mostly  green  in  color, 
and  is  known  as  Brazilian  emerald,  it  having  been  for  a  time  mistaken 
for  emerald. 

('In  the  Ural  Mountains,  near  Ekaterinburg,  crystallized  tourmaline 
occurs  in  cavities  in  granite,  accompanying  amethyst,  beryl,  topaz,  etc. 
These  crystals  often  have  a  fine  dark  red  color,  and  produce  the  gems 
known  as  Siberian  rubies.  They  are  especially  prized  in  Russia. 

\£A.lthough  the  name  tourmaline  came  from  Ceylon,  the  gem  there 
known  by  that  name  is  hyacinth.  True  tourmaline  occurs,  however,  on 
the  island  in  the  gem  gravels.  This  is  usually  of  a  yellowish-green  color, 
and  is  often  known  as  Ceylonese  chrysolite.  | 

On  the  Island  of  Elba  are  also  obtained  tourmalines,  generally  red 
in  color,  transparent,  and  well  crystallized.  They  are,  however,  not 
extensively  used  as  gems,  on  account  of  their  small  size. 


or  THE 
UNIVERSITY 

OF 


116 


LEPIDOLITE 

This  variety  of  mica  is  attractive  on  account  of  its  pink  or  lilac 
color.  It  usually  occurs  in  scaly,  granular  masses,  which  often  have 
sufficient  coherence  to  admit  of  carving  them  into  various  ornamental 
objects,  such  as  paper-weights,  small  vases,  and  boxes.  They  are  some- 
what easily  scratched,  since  the  hardness  of  lepidolite  is  only  2.5-4.  Lepi- 
dolite  is  often  known  as  lithia  mica,  on  account  of  its  content  of  lithium, 
four  per  cent  to  five  per  cent.  This  affords  a  criterion  for  the  determi- 
nation of  the  mineral,  as  a  fragment  heated  before  the  blowpipe  gives 
the  purple-red  flame  of  lithia. 

£/The  principal  European  deposit  of  lepidolite  which  has  been  used 
for  ornamental  purposes,  is  that  at  Rozena,  in  Moravia,  where  a  quantity 
of  the  mineral  of  an  especially  pleasing  rose-lilac  color  occurs.  In  the 
United  States,  lepidolite  occurs  at  Paris,  Rumford,  and  several  other 
points  in  Oxford  County,  Maine,  and  in  California,  eight  miles  from 
San  Diego.  The  deposit  at  the  latter  place  is  an  extensive  one,  and 
is  mined  for  lithia  salts.  This  lepidolite  is  penetrated  by  crystals  of  rubel- 
lite,  giving  an  effect  as  shown  in  the  colored  plate.  Although  some  of  the 
American  lepidolite  is  nearly  equal  to  the  European  in  quality  of  color, 
no  use  seems  as  yet  to  have  been  made  of  it  for  ornamental  purposes. 


117 


SPODUMENE 

Spodumene  is  the  only  one  of  the  gem  minerals  except  tourmaline 
and  lepidolite,  which  contains  the  element  lithium  in  any  large  amount. 
It  is  a  silicate  of  alumina  and  lithia,  having  the  percentages,  silica  64.5, 
alumina  27.4,  and  lithia  8.4.  It  fuses  rather  easily  before  the  blowpipe, 
and  gives  the  purple-red  color  of  lithia  to  the  flame,  making  a  con- 
venient means  of  distinguishing  the  species.  Its  hardness  is  6.5-7,  and 
specific  gravity  3.1-3.2.  Its  luster  is  vitreous.  Ordinarily  it  is  opaque, 
and  of  a  white  or  gray  color,  the  word  spodumene  being  derived  from 
the  Greek  spodios,  meaning  ash-colored. 

Spodumene  crystallizes  in  the  monoclinic  system,  often  forming  large 
crystals  up  to  four  feet  in  length.  The  use  of  spodumene  as  a  gem 
is  confined  almost  exclusively  to  a  transparent  emerald-green  variety 
occurring  in  North  Carolina,  and  a  yellow  variety,  also  transparent, 
obtained  in  Brazil.  The  emerald-green  spodumene  is  known  as  hidden- 
ite,  after  W.  E.  Hidden,  who  first  developed  it.  It  occurs  in  thin,  bladed 
crystals,  varying  from  colorless  through  yellow  to  an  emerald-green 
color.  These  afford  only  small  gems,  none  over  five  carats  being  obtain-  ^ 
able.  A  high  price  has  been  obtained  for  these,  ranging  between 
forty  dollars  and  one  hundred  dollars  per  carat.  They  are  cut  into 
step  or  table  stones,  as  this  best  exhibits  their  dichroism,  and  avoids 
the  danger  of  splitting  from  the  marked  prismatic  cleavage  present. 
All  the  hiddenite  thus  far  known  has  been  obtained  at  Stony  Point, 
Alexander  County,  North  Carolina,  and  this  locality  is  now  exhausted. 

The  yellow  spodumene,  above  referred  to  as  obtained  in  Brazil,  was 
long  thought  to  be  chrysoberyl.  Its  distinction  from  chrysoberyl,  by  the 
properties  above  mentioned,  is  easy,  although  its  use  in  jewelry  is  simi- 
lar. Pieces  of  spodumene,  of  a  beautiful  blue  color,  are  also  occasion- 
ally found  near  Diamantina,  in  Brazil.  Quite  recently  spodumene  has 
been  found  near  Pala,  San  Diego  County,  California,  in  the  form  of  large 
transparent  crystals  of  an  amethystine  hue.  These  afford  large,  hand- 
some gems,  resembling  amethyst  in  color,  but  distinguished  from  it  by 
their  dichroism  and  their  rose  to  lilac  shades.  The  name  of  kunzite  has 
been  applied  to  this  variety  of  spodumene. 

118 


453 


Topaz  with  Mica  and  Feldspar  (Russia), 
'iopaz  (Bi-axil). 


TOPAZ 
Topaz  in  Rhyolite  (Utah). 


Topaz  (Japan). 
Waterworn  Topaz  (Brazil). 


TOPAZ 

Remarkable  clearness  and  transparency,  capacity  of  taking  a  high 
polish,  and  hardness  and  weight  greater  than  that  of  quartz  are  the 
qualities  in  which  topaz  excels  as  a  gem.  Numerous  other  stones 
of  inferior  quality  masquerade  under  its  name,  however,  and  this  fact 
may  account  for  the  decline  in  popularity  which  the  stone  has  suffered 
in  recent  years.  True  topaz  is  a  silicate  of  alumina,  containing  hydroxyl 
and  fluorine.  Its  hardness  is  8,  and  it  thus  scratches  quartz.  Topaz 
is  also  remarkably  heavy,  considering  its  composition,  it  being  three 
and  one-half  times  as  heavy  as  water.  Owing  to  this  unusual  specific 
gravity,  those  accustomed  to  handling  gems  can  frequently  pick  out 
the  topaz  from  a  miscellaneous  lot  of  precious  stones  without  remov- 
ing their  wrappings. 

/  ^The  color  typically  associated  with  topaz  in  its  use  as  a  gem  is  yellow. 
Yet  the  mineral  species  exhibits  many  other  shades  of  color,  which,  when 
present  in  crystals  of  sufficient  clearness  and  purity,  answer  equally 
well  for  gem  purposes.  These  other  shades,  most  of  which  are  repre- 
sented in  the  accompanying  plate,  are  grayish,  greenish,  bluish,  and 
reddish.  Topaz  may  also  be  quite  colorless.  The  yellow  color  of  the 
Brazilian  topaz  can  be  changed  by  heating  to  a  pale  rose-pink,  and 
the  gem  is  often  treated  in  this  way.  The  degree  of  heat  employed 
is  not  high,  and  both  heating  and  cooling  must  be  performed  gradu- 
ally. The  selected  stone  may  be  packed  in  magnesia,  asbestos,  or  lime, 
and  heated  to  a  low,  red  heat,  or  it  may  be  wrapped  in  German  tinder 
and  the  latter  set  on  fire.  Only  stones  of  a  brown-yellow  color  yield 
the  pink ;  the  pale  yellow  stones  turn  white  when  so  treated.  Once  the 
pink  color  is  obtained  it  is  permanent.  The  natural  colors  of  topaz 
are  in  general  perfectly  durable,  although  some  of  the  deep  wine-yellow 
topazes  from  Russia  fade  on  exposure  to  daylight./ 

Topaz  is  infusible  before  the  blowpipe.  It  is  not  affected  by  hydro- 
chloric acid;  but  is  partially  decomposed  by  sulphuric  acid,  and  then 
yields  hydrofluoric  acid.  If  the  latter  experiment  is  tried  in  a  closed 
glass  tube,  the  formation  of  the  hydrofluoric  acid  is  made  evident  by 
the  etching  and  clouding  of  the  walls  of  the  tube.  The  powdered  stone 
should  be  mixed  with  acid  sulphate  of  potash  for  this  experiment. 

119 


\ 


Forms  of  topaz  crystals 


Another  test  for  topaz  is  to  heat  the  powdered  mineral  with  cobalt 
nitrate,  when  it  assumes  a  fine  blue  color,  due  to  the  alumina 
which  it  contains. 

The  crystals  of  topaz  belong  to  the  orthorhombic  system  of  crystal- 
lization. They  are  usually  elongated  in  the  direction  of  the  prism,  and 
have  sharp,  bright  faces.  They  vary  much  in  size,  and  often  are  large. 
One  crystal  weighing  twenty-five  pounds  was  found  in  Siberia.  Large 
gems  of  topaz  are,  therefore,  quite  easily  obtained.  Perhaps  the  largest 
cut  topaz  known  was  recently  presented  to  Pope  Leo  on  the  occasion 

of  his  silver  jubilee  (1902). 
This  stone  weighed  nearly 
four  pounds.  It  was  obtained 
originally  in  Brazil. 

A  well-marked  character- 
istic of  all  topaz  crystals  is 
their  tendency  to  cleave 
across  the  prism  parallel  with 
its  base.  Such  a  cleavage 
plane  can  be  seen  cutting  across  the  crystal  shown  in  the  upper  right- 
hand  corner  of  the  accompanying  plate.  This  cleavage  is  so  marked,  and 
the  cleavage  plane  so  bright  and  flat,  that  in  cutting  topaz  for  a  gem 
a  cleavage  surface  is  used  as  the  upper  face  of  the  gem,  and  the  other 
faces  formed  around  it.  Owing  to  this  easy  cleavage  the  owner  of  a  cut 
topaz  should  be  careful  not  to  let  the  stone  drop,  as  it  might  be  thus 
cracked  or  broken.  Topaz  takes  a  high  polish,  and  colorless  gems 
of  the  mineral  resemble  the  diamond  considerably.  They  are,  however, 
softer,  and  have  weak  double  refractive  and  dispersive  power. 

txThe  name  topaz  is  derived  from  the  Greek  name  Topazios,  which 
is  that  of  an  island  in  the  Red  Sea.  The  gem  known  to  the  ancients 
as  topaz,  however,  was  probably  not  our  topaz,  but  chrysolite.  Topaz 
usually  occurs  in  gneiss,  or  granite,  with  tourmaline,  mica,  beryl,  etc. 
In  Brazil  it  occurs  in  a  talcose  rock,  or  in  mica  slate.  It  is  sometimes 
in  sufficient  abundance  to  form  an  essential  rock  constituent.  When 
so  occurring,  however,  it  has  not  the  transparent  gem  quality,  but  is 
white  and  opaque.  Much  of  the  Brazilian  topaz  occurs  as  rolled 
pebbles,  one  of  which  is  shown  in  the  accompanying  plate.  These 
occur  in  the  beds  of  streams,  having  been  left  behind,  owing  to  their 
superior  hardness,  after  the  rock  in  which  they  were  formed  has  been 
washed  away.  When  colorless  they  are  known  in  the  region  as 
pingos  d'agua  (drops  of  water).  The  Portuguese  call  them  "  slaves'  dia- 
monds." A  stone  in  the  crown  of  Portugal,  reputed  to  be  a  diamond 

120 


of  1,680  carats  weight,  and  called  the  Braganza,  is  probably  a  topaz 
of  exceptional  clearness  and  beauty. 

The  Brazilian  topazes  come  mostly  from  the  province  of  Minas  G-eraes. 
While  those  of  greenish  and  bluish  shades  are  found  mostly  in  the  form 
of  rolled  pebbles,  the  yellow  Brazilian  topaz  is  found  in  the  mother 
rock.  This  is  a  decomposed  itacolumite,  of  a  white  or  yellow  color. 
The  principal  locality  is  near  Ouro  Preto. 

!/>The  Russian  topazes  like  that  shown  in  the  colored  plate,  come 
from  the  Imperial  mines  in  the  Urals.  Alabashka,  near  Mursinka, 
is  one  of  the  most  productive  localities.  The  crystals  occur  in  cavi- 
ties, in  granite,  and  are  accompanied  by  crystallized  smoky  quartz, 
feldspar,  and  mica.  Superb  gems  are  cut  from  these  topazes,  a  fine 
series  of  which  is  possessed  in  this  country  by  the  Field  Columbian 
Museum  and  the  United  States  National  Museum.  The  Russian  mines 
are  owned  and  operated  by  the  Russian  Government,  and  the  finest 
specimens  are  reserved  for  the  Imperial  Cabinet.'  ^In  the  southern 
Urals,  in  the  gold  washings  of  the  River  Sanarka.  yellow  topazes  are 

found  closely  resembling  those  of  Brazil.     Associated  with  them  are 
a  .  j 

amethysts,  rubies,  chrysoberyls,  and  many  other  precious  stones. /^Topaz 
crystals  of  good  size  and  color  are  found  quite  abundantly  in  Japan, 
although  they  have  not  yet  been  cut  for  gems  to  any  extent.  There 
are  many  localities  in  the  United  States  where  topaz  occurs,  and  it 
is  often  of  gem  quality.  The  group  shown  in  the  plate  illustrates 
the  occurrence  of  topaz  at  Thomas  Mountain,  Utah,  a  locality  forty 
miles  north  of  Sevier  Lake.  These  crystals  are  found  in  cavities  in 
the  rock.  They  are  never  very  large,  but  are  usually  clear  and  bright. 
They  occur  in  somewhat  similar  fashion  at  Nathrop,  Colorado.  In  the 
Eastern  States  topaz  was  first  found  at  Trumbull,  Connecticut.  It 
is  here  quite  opaque,  and  not  suitable  for  gem  purposes.  Good  gem 
topaz  has  been  found  at  Huntington  and  Middletown,  Connecticut, 
however,  and  at  North  Chatham,  New  Hampshire.  In  these  locali- 
ties it  occurs  in  pegmatitic  granite. 

Of  other  stones  which  are  sold  under  the  name  of  topaz,  the  most 
common  is  the  so-called  Spanish  or  Saxon  topaz.  This  is  simply  smoky 
quartz,  heated  until  it  turns  a  yellow  color.  It  can  easily  be  distin- 
guished from  true  topaz  by  the  properties  of  the  latter  above  given. 

At  the  present  time  it  is  also  quite  a  common  practice  to  vend 
ordinary  colorless  quartz  under  the  name  of  topaz.  These  practices 
are  harmful  to  the  reputation  of  true  topaz,  as  these  forms  of  quartz 
lack  several  of  the  desirable  qualities  of  that  stone.  The  so-called 
Oriental  topaz  is  a  yellow  form  of  corundum.  It  is  heavier  and  harder 

121 


than  true  topaz,  and  more  valuable.  fLAbout  forty  years  ago  topaz  was 
quite  popular  as  a  gem,  and  commanded  three  or  four  times  its  present 
price.  At  the  present  time  a  stone  weighing  several  carats  may  be 
bought  for  two  or  three  dollars.  ) 

Topaz  is  often  referred  to  by  ancient  writers,  and  is  mentioned  in 
the  Bible  as  one  of  the  stones  to  be  put  in  the  ephod  of  the  high 
priest,  as  one  of  the  gems  worn  by  the  king  of  Tyre,  and  as  forming 
one  of  the  gates  of  the  Holy  City.  The  gem  referred  to  in  these 
instances  is,  however,  the  modern  chrysolite,  while  where  chrysolite 
is  spoken  of  our  topaz  is  usually  meant. 

A  topaz  presented  by  Lady  Hildegarde,  wife  of  Theoderic,  Count 
of  Holland,  to  a  monastery  in  her  native  town,  emitted  at  night, 
according  to  legend,  a  light  so  brilliant  that  in  the  chapel  where  it 
was  kept  prayers  could  be  read  at  night  without  the  aid  of  a  light; 
a  statement  which  might  well  be  true  if  the  monks  knew  the  pray- 
ers by  heart. 

The  spiritual  qualities  associated  with  topaz  are  fruitfulness  and 
faithfulness.  It  is  also  said  to  confer  cheerfulness  upon  its  wearer. 
The  ancients  believed  that  it  calmed  the  passions  and  prevented  bad 
dreams ;  that  it  discovered  poison  by  becoming  obscured  when  in  con- 
tact with  it;  that  it  quenched  the  heat  of  boiling  water,  and  that  its 
powers  increased  and  decreased  with  the  increase  and  decrease  of  the 
moon.  Also  that  a  topaz  held  in  the  hand  of  a  woman  at  child- 
birth would  lessen  her  suffering,  and  that  powdered  and  taken  in  wine 
it  would  cure  asthma  and  insomnia. 


122 


CYANITB 

(DISTIIENE) 

The  character  of  this  mineral  in  its  employment  as  a  gem  is  indicated 
by  the  derivation  of  its  name,  which  is  from  the  Greek  word  kuanos, 
meaning  blue.  While  cyanite  at  times  presents  other  colors,  such  as 
gray,  green,  black,  and  white,  only  the  transparent  blue  variety  is  used 
for  gem  purposes.  This  is  often  dark  blue,  resembling  sapphire  in 
color,  and  cut  stones  may  thus  considerably  resemble  the  latter.  Like 
sapphire,  cyanite  is  largely  composed  of  aluminum,  but  it  is  a  silicate 
of  this  metal  instead  of  an  oxide.  The  percentage  composition  of 
typical  cyanite  is  alumina  63.2,  silica  36.8.  Cyanite  is  not  as  hard  as 
sapphire,  being  5-7  in  hardness.  One  of  its  peculiarities  is  that  the 
hardness  differs  in  two  directions.  If  one  of  the  broad  blades  of  the 
mineral  be  scratched  in  one  direction  a  hardness  of  5  is  observed,  while 
in  a  direction  at  right  angles  to  this  the  hardness  will  be  found  to  be  7. 
The  name  of  disthene,  by  which  cyanite  is  sometimes  known,  refers  to 
the  above  differences,  it  being  derived  from  dis,  twice,  or  of  two  kinds, 
and  sthenos,  strong.  Cyanite  usually  shows  slight  differences  of  color  in 
different  directions.  It  has  a  marked  cleavage,  which  somewhat  inter- 
feres with  its  use  as  a  gem,  cracks  being  easily  started  in  this  direction. 
Its  specific  gravity  is  comparatively  high,  being  3.55-3.65,  nearly  but  not 
quite  equal  to  that  of  sapphire.  Its  crystals  belong  to  the  triclinic  system. 

Its  occurrence  is  usually  in  mica  schists  and  gneisses,  it  being  often 
accompanied  by  garnet  and  staurolite.  The  decay  of  the  mother  rocks 
leaves  it  in  form  of  rolled  pebbles,  in  which  manner  it  occurs  in  Russia, 
India,  and  Brazil.  Cyanite  from  all  these  localities  affords  good  stones 
for  cutting,  Monte  Campione,  in  the  St.  Gothard  region  of  Switzerland, 
furnishes  some  of  the  finest  crystals  known.  Nearly  all  that  has  been 
used  for  gem  purposes  in  this  country  has  been  obtained  near  Bakers- 
ville,  North  Carolina.  The  comparative  softness  of  cyanite  is  a  bar  to 
its  extensive  use  as  a  gem,  although  in  respect  to  color  and  luster  it  is  of 
a  pleasing  character. 


123 


ANDALUSITE 

This  mineral  has  the  same  chemical  composition  as  cyanite,  it  being 
a  simple  aluminum  silicate.  It  differs,  however,  from  that  mineral  in 
color,  specific  gravity,  system  of  crystallization  and  various  other  proper- 
ties, so  that  there  is  little  danger  of  mistaking  the  two. 

Andalusite  occurs  generally  as  an  opaque  mineral,  commonly  in  argil- 
laceous and  mica  schists.  The  transparent  pieces  cut  for  gems  are  obtained 
almost  entirely  from  the  province  of  Minas  Geraes,  Brazil,  where  they 
occur  in  the  beds  of  streams,  together  with  topaz.  These  transparent 
pebbles  have  a  pale  green  color  in  one  direction  and  in  another  are 
brownish  red.  This  difference  of  color  is  due  to  the  pleochroism  of  the 
mineral,  which  is  strong,  and  the  directions  of  which  should  be  borne  in 
mind  in  cutting.  It  is  when  looked  at  in  the  direction  of  the  vertical 
axis  that  the  reddish  color  of  andalusite  is  apparent,  while  at  right 
angles  to  this  the  green  color  appears. 

Andalusite  crystallizes  in  the  orthorhombic  system,  the  crystals 
usually  taking  the  form  of  nearly  square  prisms.  It  has  a  marked 
prismatic  cleavage,  which  does  not,  however,  interfere  with  the  cutting  of 
it  to  any  extent.  Its  luster  is  vitreous.  In  hardness  it  is  somewhat 
superior  to  quartz,  the  degree  of  hardness  being  7.5.  The  specific  gravity 
is  3.16-3.20.  Like  cyanite,  andalusite  is  infusible  before  the  blowpipe, 
and  is  not  attacked  by  acids. 

In  addition  to  the  use  of  the  transparent  forms  of  andalusite,  men- 
tion should  be  made  of  the  fact  that  sections  of  the  opaque  crystals  are 

sometimes  worn,  being 
prized  on  account  of  the 
cross-like  markings 
which  they  contain. 
These  result  from  the 

Sections  of  andalusite  crystal  showing  cross-like  markings        shape    taken     by     inclu- 

sions  of    carbonaceous 

matter  hi  the  crystal,  which  usually  extend  from  end  to  end  of 
the  same.  Peasants  of  Brittany  prize  these  especially  as  charms, 
believing  them  of  miraculous  origin.  This  variety  of  andalusite  is -tech- 
nically known  as  chiastolite,  from  the  Greek  chiastos,  meaning  arranged 

124 


diagonally,  and  also  as  made,  in  allusion  to  the  use  of  the  "mascle"  in 
heraldry,  which  signifies  a  rhomb  with  open  center.  The  name  andalu- 
site  is  from  the  province  of  Andalusia  in  Spain,  whence  the  mineral  was 
first  described.  Chiastolites  are  found  at  various  points  in  New  England 
and  in  California  in  this  country,  but  sale  for  them  is  to  be  found  chiefly 
abroad.  Kunz  describes  andalusite  of  a  pink  color,  capable  of  affording 
transparent  gems,  which  is  obtainable  at  Westford,  Massachusetts,  and 
Standish,  Maine. 


125 


STAUROLITE 

This  mineral  when  sufficiently  transparent  to  make  a  gem,  furnishes 
a  dark,  brownish  red  stone,  not  unlike  some  varieties  of  garnet  in  color. 
It  is  similar  also  to  garnet  in  hardness,  7-7.5,  and  specific  gravity, 
this  being  about  3.7.  It  differs,  however,  in  crystallizing  in  the 
orthorhombic  system,  and  hence  it  is  doubly  refracting.  The  crystals 
usually  have  the  shape  of  six-sided  prisms,  often  grouped  in  the  shape  of  a 
cross,  the  latter  habit  giving  the  mineral  its  name,  from  the  Greek,  stauros, 

a  cross.  Groups  of  this  shape  are  found 
abundantly  in  Fannin  County,  Georgia,  and 
are  there  known  as  fairy  stones,  under  the 
belief  that  fairies  make  them.  The  peasants 
of  Brittany  wear  similar  crystals  as  charms, 
believing  them  of  miraculous  origin.  The 
Penitentes  of  New  Mexico  are  said  also  to 

have  great  reverence  for  the  stone,  each  member  of  the  sect  being 
accustomed  to  wear  one  around  his  neck.  A  traveler  endeavoring 
to  buy  one  found  it  impossible  to  do  so,  the  owner  saying  that  he  would 
sooner  part  with  one  of  his  children.  The  stone  had  been  blessed  by 
the  priest,  and  its  possessor  believed  that  it  insured  him  a  long  and 
happy  life,  and  protected  him  from  all  ailments  and  accidents. 

In  composition  staurolite  is  a  hydrous  silicate  of  iron,  magnesium, 
and  aluminum.  It  is  generally  infusible,  and  but  slightly  attacked  by 
acids.  Rolled  pebbles  of  staurolite  occur  in  the  gem  gravels  of  Brazil, 
and  crystals  suitable  for  cutting  into  transparent  stones  come  from  Swit- 
zerland and  Moravia.  Staurolite  is  a  common  mineral  in  mica  schists, 
and  in  such  a  matrix  occurs  in  several  localities  in  this  country,  but  no 
transparent  crystals  have  been  found  here. 


126 


or 


559 


Almandine  Garnet  (Alaska). 

Essonite  Garnet,  cut. 
Dem  an  told  Garnet,  cut. 
Demantoid  Garnet  (Ural  Mts.). 


Alniandite  Garnet,  cut. 


"Cape  Ruby,"  cut. 


Essonite  Garnet  and  Diopside  (Italy). 
Chrysolite  crystal. 


Epidote  (Knappenwand,  Austria). 

Epidote,  cut. 
.Chrysolite,  cut. 
Pyrope  Garnet  (Bohemia). 


GARNET 

This  mineral  exhibits  many  varieties  of  color  and  of  composition. 
The  color  probably  most  often  thought  of  in  connection  with  it  is  dark 
red,  but  it  would  be  a  mistake  to  suppose  this  the  only  color  which  it 
may  manifest.  Green,  red,  rose,  and  brown  are  other  colors  which  garnet 
transparent  enough  to  be  used  as  gems  exhibits,  while  among  opaque 
garnets  may  be  found  black  and  many  varieties  of  the  shades  above 
mentioned. 

These  variations  of  color  are  more  or  less  connected  with  differences 
of  composition  which  it  may  be  well  first  of  all  to  consider.  Garnet  as 
a  mineral  is  a  silicate.  United  with  silica  the  element  most  commonly 
occurring  is  aluminum.  If  calcium  be  united  with  these  two,  the  variety 
of  garnet  known  as  grossularite,  or  essonite,  or  cinnamon  stone,  is  pro- 
duced. If  magnesium  takes  the  place  of  calcium,  then  pyrope  is  formed. 
If  iron,  we  have  almandite,  and  if  manganese,  spessartite.  Another 
variety  of  garnet,  andradite,  is  composed  of  calcium  and  iron  in  com- 
bination with  silica,  and  still  another,  uvarovite,  of  calcium,  chromium, 
and  silica.  Though  they  seem  to  differ  so  much  in  composition,  all  kinds 
of  garnet  crystallize  in  the  same  system,  and  are  closely  allied  in  all 
their  properties,  so  that  it  is  an  easy  matter  to  distinguish  garnet 
of  any  variety  from  other  minerals. 


Forms  of  garnet  crystals 

Garnet  crystals  may  be  of  the  twelve-sided  form  known  as  dodeca- 
hedrons, the  faces  of  which  have  the  shape  of  rhombs ;  or  the  twenty-four- 
sided  form,  known  as  trapezohedrons,  the  faces  of  which  have  the  shape 
of  trapeziums.  Quite  as  commonly  occur  crystals  which  are  combina- 
tions of  these  two  forms,  and  then  exhibit  thirty-six  faces,  as  in  the  crystal 

127 


from  Alaska  shown  in  the  accompanying  colored  plate.  Sometimes  the 
crystals  attain  considerable  size.  Perfect  ones  from  Colorado  weighing 
fifteen  pounds  are  known,  and  some  two  feet  in  diameter  are  reported 
from  North  Carolina.  A  curious  feature  of  garnet  crystals  is  that  of  often 
inclosing  other  minerals.  The  garnets  from  New  Mexico,  for  instance, 
when  broken  open  are  sometimes  found  to  contain  a  small  grain  of 
quartz.  In  the  crystals  from  East  Woodstock,  Maine,  only  the  outside 
shell  is  garnet,  and  the  interior  is  calcite.  Other  crystals  are  made  up 
of  layers  of  garnet  and  some  other  mineral. 

Garnet  has  a  strong  tendency  to  crystallize,  and  hence  is  usually 
found  as  crystals.  The  grains  of  garnet  found  in  the  sands  of  river  beds 
and  on  beaches,  though  not  often  showing  crystal  form,  may  be  really 
fragments  of  crystals.  Garnet  is  one  of  the  most  common  constituents 
of  such  sands  because  of  its  hardness  and  power  of  resisting  decay.  These 
properties  enable  it  to  endure  after  the  other  ingredients  of  the  rocks  of 
which  it  formed  a  part  have  been  worn  away.  It  is  quite  heavy  as  com- 
pared with  the  quartz,  of  which  the  sand  is  mostly  composed,  and  hence 
continually  accumulates  on  a  beach,  while  the  quartz  is  in  part  blown 
away.  In  such  localities  it  will  always  be  found  near  the  water  line, 
because  the  waves,  on  account  of  its  weight,  can  carry  it  but  a  slight 
distance  inland.  Practically  all  garnet  is  three  and  one-half  times  as 
heavy  as  water,  and  some  four  times  as  heavy.  As  a  rule,  it  is 
somewhat  harder  than  quartz,  its  hardness  being  1\  in  the  scale  of  which 
quartz  is  7.  Some  varieties  are,  however,  somewhat  softer.  Most  varie- 
ties of  garnet  fuse  quite  readily  before  the  blowpipe,  and  the  globules 
thus  formed  will  be  magnetic  if  the  garnet  contains  much  iron.  The 
green  garnet,  uvarovite,  is  almost  infusible,  however.  Garnet  is  not 
much  affected  by  ordinary  acids,  although  it  may  be  somewhat  decom- 
posed by  long  heating. 

The  name  garnet  is  said  by  some  authorities  to  come  from  the  Latin 
word  granatus,  meaning  like  a  grain,  and  to  have  arisen  in  allusion  to 
the  resemblance  of  its  crystals  in  color  and  size  to  the  seeds  of  the 
pomegranate.  The  German  word  for  garnet,  granat,  is  the  same  as  the 
Latin  word.  Others  think  the  word  derived  from  the  Latin  name  of  the 
cochineal  insect,  in  allusion  to  a  similarity  in  color. 

The  use  of  garnet  for  gem  purposes  seems  to  date  back  to  the  earliest 
times.  Among  the  ornaments  adorning  the  oldest  Egyptian  mummies 
there  are  frequently  found  necklaces  containing  garnet.  The  Romans 
prized  the  stone  highly,  and  it  is  a  gem  much  used  at  the  present 
day,  its  hardness  and  durability  and  richness  and  permanency  of  color 
giving  it  qualities  desirable  for  a  precious  stone. 

128 


Two  varieties  of  garnet,  almandite  and  pyrope,  may  exhibit  the  dark 
blood-red  color  especially  ascribed  to  garnet.  Almandite  or  almandine 
garnet  derives  its  name  from  Alabanda,  a  city  of  Asia  Minor,  in  the 
ancient  district  of  Caria,  whence  garnet  was  first  brought  to  the  Romans. 
*  The  finest  almandite  for  a  long  time  came  from  near  the  city  of  Sirian, 
in  the  old  province  of  Pegu,  Lower  Burmah.  While  this  was  the  center 
of  supply,  it  is  not  known  just  where  the  garnets  were  obtained.  Such 
garnets  are  still  known  as  "Sirian"  garnets.  Their  color  tends  toward 
the  violet  of  the  ruby,  and  gives  them  a  high  value,  j^liere  are  several 
localities  in  northern  India  where  almandite  is  mined  on  a  large  scale, 
and  the  stone  is  much  used  in  Indian  jewelry.  Some  of  these  localities 
are  Condapilly,  Sarwar,  and  Cacoria/  Almandite  is  also  found  in  Brazil, 
in  Australia,  in  several  localities  in  the  Alps,  and  in  the  United  States. 
Stones  from  all  these  regions  are  found  suitable  for  cutting,  the  only 
qualifications  needed  being  sufficient  size  and  transparency  and  good 
color.  The  almandite  of  Alaska  shown  in  the  accompanying  plate  occurs 
in  great  quantities  near  the  mouth  of  the  Stickeen  River,  but  has  not 
been  extensively  cut  on  account  of  its  being  too  opaque.  Almandite 
usually  occurs  in  metamorphic  rocks,  such  as  gneisses  or  mica  schists; 
also  in  granite.  It  is  also  found  in  many  gem  gravels.  From  the  ruby 
it  can  be  distinguished,  as  can  all  varieties  of  garnet,  by  its  lower  hard- 
ness and  single  refraction  of  light.  In  artificial  light,  too,  it  borrows 
a  yellow  tint,  rendering  it  less  pleasing,  while  the  color  of  ruby  grows 
more  intense.  When  almandite  tends  toward  a  brownish-red  color  it 
is  known  as  vermeille. 

Pyrope,  the  magnesian  variety  of  garnet,  does  not  differ  much  in 
color  from  almandite.  Both  are  dark  red,  but  while  almandite  tends 
toward  a  violet  tone,  pyrope  shades  toward  yellow.  Pyrope  is  lighter 
than  almandite,  the  specific  gravity  being  3.7  to  3.8,  while  that  of 
almandite  is  4.1  to  4.3.  It  is  also  less  easily  fusible.  It  rarely  occurs 
in  crystals,  and  where  found  in  place  is  always  associated  with  the  mag- 
nesium-bearing rocks,  peridotite  or  serpentine.  It  is  thus  probably  always 
of  eruptive  origin.  Pyrope  is  a  characteristic  constituent  of  the  diamond- 
bearing  rock  of  South  Africa,  and  is  the  stone  known  in  trade  as  u  Cape 
ruby."  These  garnets  afford  excellent  gems.l^The  home  of  the  pyrope, 
however,  is,  and  has  been  for  many  centuries,  Bohemia.  Here  it  is  found 
in  many  localities,  but  chiefly  in  the  northwestern  part,  near  Teplitz  and 
Bilin.  The  garnets  are  found  in  a  gravel  or  conglomerate  of  Creta- 
ceous age,  resulting  from  the  decomposition  of  a  serpentine.  Sometimes, 
however,  they  are  found  in  the  matrix,  and  are  then  often  associated 
with  a  brown  opal.  They  are  found  by  digging  and  separated  by  wash- 

129 


Mfag.  Though  of  good  quality  the  stones  are  small,  those  as  large  as  a 
hazelnut  being  found  but  rarely.  Although  the  Bohemian  garnets  have 
been  known  for  many  centuries,  the  industry  of  mining  and  cutting  them 
on  a  large  scale  is  said  not  to  have  assumed  any  special  proportions  until 
the  advent  of  foreigners  to  Karlsbad.  They  spread  a  knowledge  of  the 
stones  to  other  countries,  and  a  demand  sprang  up  which  has  led 
to  the  establishment  of  a  great  industry,  and  made  Bohemia  the  garnet 
center  of  the  world.  There  are  over  three  thousand  men  employed  at 
the  present  time  simply  in  cutting  the  stones,  and  if  to  these  be  added 
the  number  of  miners  and  gold  and  silver  smiths  occupied  in  the  mining 
and  mounting  of  the  garnets,  it  is  estimated  that  a  total  of  ten  thousand 
persons  is  engaged  in  the  Bohemian  garnet  industry.  The  stones  are 
used  not  alone  for  jewelry  and  for  ornamenting  gold  and  silver  plate,  but 
also  extensively  for  watch  jewels  and  for  polishing,  f  Excellent  pyropes 
are  found  in  Arizona,  New  Mexico,  and  southern  Colorado  in  our  own 
country.  They  occur  in  the  beds  of  streams  as  rolled  pebbles,  and  often 
associated  with  the  green  chrysolite  or  peridot  of  the  eruptive  rock  from 
which  they  came.  They  are  especially  abundant  about  anthills,  being 
removed  by  the  ants  because  their  size  stands  in  the  way  of  the  excava- 
tions of  the  busy  insects.  The  name  pyrope  comes  from  the  Greek  word 
for  fire,  and  is  applied  on  account  of  the  color  of  the  stone. 

Of  quite  similar  origin  is  the  name  carbuncle,  a  term  applied  to 
nearly  all  fiery  red  stones  in  Roman  times,  but  now  used  to  designate 
garnets  cut  in  the  oval  form  known  as  cabochon.  The  word  carbuncle 
comes  from  the  Latin  word  carbo,  coal,  and  refers  to  the  internal  fire-like 
color  and  reflection  of  garnets. 

The  calcium-aluminum  variety  of  garnet,  called  grossularite,  cinna- 
mon stone,  or  essonite,  is  less  used  in  jewelry  than  those  above  mentioned. 
It  is  usually  yellow  to  brown  in  color,  but  may  be  rose-red  or  pink.  The 
yellow  grossularites  resemble  in  color  the  hyacinth,  and  are  sometimes 
sold  in  place  of  the  latter,  but  true  hyacinth  is  much  heavier  and 
doubly  refracting.^  kAbout  the  only  essonites  or  cinnamon  stones  avail- 
able for  gems  come  from  Ceylon.  These  are  of  good  size  and  color.  \ 
Those  from  Italy,  shown  in  the  accompanying  plate,  are  too  small 
to  cut  into  gems,  but  surrounded  as  they  are  by  light  green  chlorite 
and  pyroxene,  make  very  pretty  mineral  specimens.  Grossularite  is 
almost  always  found  in  crystalline  limestone. 

Green  garnets  are  of  two  kinds,  the  calcium-iron  garnet,  known  as 
demantoid,  and  the  calcium-chromium  garnet,  known  as  uvarovite.  The 
demantoid  garnets  come  only  from  the  Urals.  They  have  a  rich  green 
color,  and  make  beautiful  gems  when  clear  and  flawless.  The  name 

130 


demantoid  refers  to  the  diamond-like  luster  which  they  possess.  The 
stone  is  also  known  as  "  Uralian  emerald."  Uvarovite,  named  for  Count 
Uvarov  of  Russia,  also  makes  valuable  gems  if  found  in  pieces  of  suffi- 
cient size  and  luster.  It  is  found  in  Russia,  in  Pennsylvania,  and  in 
Canada. 

That  garnet  has  been  known  and  used  from  the  earliest  times 
has  already  been  remarked.  Under  the  name  of  carbuncle  mention  is 
made  of  it  in  the  literature  of  all  ages,  the  feature  noted  being  usually 
the  brilliant,  fiery  light  which  it  gives  iorth.  According  to  the  Talmud, 
the  only  light  which  Noah  had  in  the  ark  was  afforded  by  a  carbuncle, 
and  there  are  many  Oriental  tales  regarding  the  size  and  brilliancy  of 
carbuncles  owned  by  the  potentates  of  the  East.  Occasionally  carbuncles 
were  engraved,  and  some  fine  garnet  intaglios  are  still  known.  The 
greater  abundance  of  the  stone  in  modern  times  has  led  to  its  being  less 
highly  prized  than  formerly,  and  to  its  being  put  to  other  uses  than  mere 
adornment,  but  it  perhaps  contributes  more  largely  to  the  comfort  and 
happiness  of  the  world  as  it  is  now  used  than  could  ever  have  been  the 
case  when  it  was  the  property  only  of  kings.  The  virtues  ascribed  to 
the  garnet  in  earlier  times  were  similar  to  those  of  the  ruby,  but  in  less 
degree.  It  was  emblematic  of  constancy,  gave  and  preserved  health,  and 
reconciled  differences  between  friends.  It  kept  off  plague  and  thunder 
if  suspended  from  the  neck,  and  increased  riches  and  honors. 


131 


CHRYSOLITE 

This  mineral  is  known  among  the  gems  by  many  names.  It  is 
often  called  chrysoberyl  by  jewelers,  while  the  true  chrysoberyl  is  called 
chrysolite.  It  is  also  known  by  different  names,  according  to  its  color, 
it  being  called  peridot  when  of  a  deep  olive-green,  olivine  when  of  a  yel- 
lowish-green, and  chrysolite  when  of  a  lighter  or  golden-yellow  color. 
The  name  chrysolite  means  gold  stone.  Again,  some  so-called  emer- 
alds are  really  chrysolite,  a  notable  case  being  those  shown  in  connec- 
tion with  the  Three  Magi  in  the  Cathedral  at  Cologne.  The  so-called 
"Oriental  chrysolite"  is  yellowish-green  sapphire;  "Ceylonese  chrys- 
olite" is  olive-green  tourmaline ;  "  Saxon  chrysolite  "  is  greenish-yellow 
topaz;  " false  chrysolite "  is  moldavite;  " Cape  chrysolite  "  is  prehnite, 
and  so  on.  The  various  designations  have  evidently  arisen  by  con- 
founding different  minerals  similar  in  color,  but  it  is  an  easy  matter 
in  any  case  to  distinguish  the  minerals  by  a  test  of  their  physical  and 
chemical  properties.  One  feature  distinguishing  chrysolite  from  most 
other  gems  is  its  relatively  low  hardness,  which  is  6f .  It  will  thus 
scratch  feldspar,  but  is  scratched  by  quartz  and  most  other  gems.  Again, 
it  is  relatively  heavy,  its  specific  gravity  being  between  3.3  and  3.4.  Its 
luster,  too,  while  vitreous,  has  a  slightly  oily  character,  which  can  be 
detected  by  a  little  experience.  Chrysolite  is  easily  dissolved  by  the 
common  acids,  especially  if  powdered  and  warmed,  the  silica  separating 
in  a  gelatinous  form,  which  is  quite  characteristic.  In  composition  it  is 
a  silicate  of  magnesium  and  iron,  the  relative  percentages  of  the  two 
latter  elements  varying.  In  gem  chrysolite  the  percentage  of  iron  is 
usually  low,  and  a  typical  composition  would  be:  silica,  41%,  magnesia, 
49.2 % ,  and  iron  protoxide,  9.8 % .  Before  the  blowpipe  chrysolite  whitens, 
but  is  generally  infusible.  It  crystallizes  in  the  orthorhombic  system, 
and  is  hence  doubly  refracting.  The  crystals  have  good  cleavage  in 
one  direction  and  partial  cleavage  in  another.  The  fracture  is  con- 
choidal.  Chrysolite  is  a  common  constituent  of  eruptive  rocks,  but  in 
grains  too  small  and  too  opaque  to  be  used  for  gems. 

Whence  the  large,  transparent  pieces  of  chrysolite  used  for  gems 
are  obtained  does  not  seem  to  be  known.  They  are  reported  to  come 
from  the  Levant,  from  Burmah,  from  Ceylon,  from  Egypt,  and  from 

132 


Brazil;  but  the  exact  locality  in  none  of  these  countries  has  yet  been 
ascertained  by  writers.  Kunz  states  that  all  the  chrysolite  sold  in 
modern  times  is  taken  out  of  old  jewelry,  often  two  centuries  old,  so 
that  it  is  likely  that  the  old  localities  are  either  forgotten  or  ex- 
hausted. Recently,  however,  quite  an  amount  of  good  chrysolite  has 
.  come  from  a  locality  in  Upper  Egypt,  near  the  Red  Sea,  and  this  is 
doubtless  one  of  the  old  sources  of  supply.  The  chrysolites  at  present 
available  are  not  of  very  large  size,  rarely  exceeding  an  inch  in  diam- 
eter. They  are,  however,  of  fine  color  and  transparency,  and  make 
a  desirable  gem  when  not  exposed  to  hard  usage.  For  ring  stones 
they  scratch  and  wear  away  too  easily.  Excellent  small  chrysolites 
come  from  Arizona  and  New  Mexico,  being  found  in  sand  in  connec- 
tion with  the  pyrope  garnets  previously  mentioned.  The  chrysolite 
is  locally  called  "Job's  tears,"  on  account  of  its  pitted  appearance. 
Chrysolite  is  an  essential  constituent  of  meteorites,  and  the  grains 
sometimes  occur  in  these  bodies  of  sufficient  size  and  transparency 
to  be  cut  into  gems  of  about  a  carat  each.  Such  stones  have  a  peculiar 
interest  on  account  of  their  origin. 

Chrysolite  is  frequently  mentioned  in  the  Bible  and  in  ancient  litera- 
ture; but  it  is  pretty  certain  that  much  of  the  chrysolite  so  named 
was  our  topaz.  If  this  is  true,  the  chrysolite  of  the  ancients  was 
found  on  the  island  of  Topazios,  in  the  Red  Sea.  Diodones  Siculus 
says  of  the  stone  there  that  it  was  not  discernible  by  day,  but  was 
bright  at  night,  so  that  it  could  be  seen  by  patrols.  They  would 
cover  the  luminous  spot  with  a  vase,  and  the  next  day  come  and  cut 
out  the  rock  at  the  place  indicated,  when,  upon  polishing,  the  gem 
would  appear.  The  name  chrysolite  was  also  applied  in  former  times 
to  a  number  of  other  yellow  gems,  such  as  zircon  and  beryl,  stones 
of  a  similar  color  being  then  usually  classed  together.  Powdered  chryso- 
lite was  used  as  a  remedy  for  asthma,  and  held  under  the  tongue  was 
believed  to  lessen  thirst  in  fever. 


133 


EPIDOTE 

This  is  a  mineral  possessing  several  interesting  characters,  and  hav- 
ing many  qualities  desired  in  gems,  yet  its  use  in  jewelry  is  very 
limited.  It  is  comparatively  common  as  one  of  the  constituent  min- 
erals of  metamorphic  rocks,  but  in  its  ordinary  occurrences  it  is  not 
suitable  for  gem  purposes.  It  is  only  when  occurring  in  large,  trans- 
parent crystals  that  pieces  suitable  for  cutting  can  be  obtained.  Its 
peculiar  green  color  is  one  of  its  most  striking  characters,  enabling  it 
nearly  always  to  be  recognized.  This  color  is  a  yellowish  green,  known 
as  pistachio  -  green,  and  is  hardly  possessed  by  another  mineral.  It 
frequently,  however,  shades  to  black  on  the  one  hand  and  brown  on 
the  other,  so  that  it  cannot  be  taken  alone  as  a  criterion  for  determi- 
nation. Epidote  is  quite  strongly  pleochroic ;  that  is,  it  exhibits  differ- 
ent colors  in  different  directions,  being  often  green  in  one  direction, 
brown  in  another,  and  yellow  in  another.  It  is  usually  cut  so  as 
to  show  the  green  color,  and  the  stone  must  generally  be  made  quite 
thin  to  get  the  proper  transparency.  Epidote  is  a  rather  hard  and 
heavy  mineral,  its  hardness  being  nearly  equal  to  that  of  quartz,  and 
its  specific  gravity  3.2  to  3.5.  It  is  brittle,  and  has  a  basal  cleavage. 
Its  luster  is  vitreous  to  resinous. 

In  composition  it  is  a  hydrous  silicate  of  calcium,  aluminum,  and 
iron,  the  darkness  of  its  color  increasing  with  a  larger  proportion 
of  iron.  It  is  fusible  before  the  blowpipe,  but  unattacked  by  acids 
before  fusing,  flfthe  finest  crystals  of  epidote  for  cutting  come  from 
the  Knappenwand,  in  the  valley  of  the  Pinzgau,  Austrian  Tyrol. 
Specimens  of  these  are  shown  in  the  accompanying  colored  plate. 
This  occurrence  was  discovered  in  1866.  |  Quite  recently  an  occurrence 
of  epidote,  more  beautifully  crystallized  even  than  that  of  the  Knap- 
penwand, was  discovered  on  Prince  of  Wales  Island,  Alaska ;  but  unfor- 
tunately these  specimens  are  too  opaque  for  cutting.  Being  a  rather 
heavy  mineral,  epidote  lingers  among  the  pebbles  of  stream  beds,  and 
material  suitable  for  cutting  is  hence  sometimes  found  in  this  way. 
Brazil  and  North  Carolina  are  localities  where  epidote  of  this  sort 
has  been  found. 

134 


VESUVIANITE 

(IDOCRASE) 

This  mineral  affords  transparent  stones  of  pale  brown,  green,  or  yel- 
low colors,  which  closely  resemble  in  appearance  cut  gems  of  smoky 
quartz,  tourmaline,  chrysolite,  hyacinth,  or  essonite.  They  have  a  rich 
luster  due  to  a  combination  of  resinous  and  vitreous  characters,  and 
are  sufficiently  dichroic  to  be  of  interest  from  that  point  of  view. 
Nearly  all  the  cut  stones  come  from  the  occurrence  at  Mount  Vesuvius 
(whence  the  mineral  obtains  its  name),  or  from  one  on  the  Mussa  Alp, 
in  the  Ala  valley  of  the  Piedmont  plateau,  Italy.  The  crystals  from 
Vesuvius  are  generally  brownish  to  colorless,  while  those  of  the  Pied- 
mont are  green. 

The  hardness  of  vesuvianite  is  6.5,  sufficient  to  give  it  a  fair  wear- 
ing quality.  Its  specific  gravity  is  3.35  to  3.45.  In  composition  it 
is  a  complex  silicate,  chiefly  of  aluminum  and  calcium.  It  is  fusible 
before  the  blowpipe.  It  has  a  strong  tendency  to  crystallize,  the  crystals 
belonging  to  the  tetragonal  system,  and  usually  appearing  essentially 
as  short,  stout  prisms. 

It  is  not  an  uncommon  mineral,  but  is  usually  too  opaque  to  make 
desirable  gems.  Its  occurrence  is  especially  associated  with  limestone, 
either  as  the  result  of  metamorphism  or  direct  volcanic  eruption,  as  at 
Vesuvius.  A  yellowish  brown  variety,  known  as  xanthite,  occurs  at 
Amity,  New  York,  and  an  occurrence  on  the  Vilui  River,  near  Lake 
Baikal,  Siberia,  is  known  as  viluite. 

The  cut  stones  are  made  exclusively  from  clear  crystals,  which  rarely 
afford  stones  exceeding  a  few  carats  in  size.  The  step  or  table  cut  is 
the  form  usually  given  the  stones. 


135 


IOLITE 

(DICHROITE,    CORDIERITE) 

Of  the  different  names  by  which  this  mineral  is  known,  cordierite 
is  in  honor  of  the  French  geologist  Cordier  —  while  the  two  others 
indicate  important  characters  of  the  mineral — first,  that  it  is  of  a  violet 
color  (Greek,  ion,  violet,  and  lithos,  stone);  and  second,  that  it  has 
two  colors  (Greek,  dichroos,  two-colored). 

When  cut  as  a  gem  the  stone  is  usually  known  as  water  sapphire, 
or  saphir  deau.  In  color  it  resembles  the  sapphire  closely,  although 
the  shade  of  blue  which  it  exhibits  is  that  known  as  Berlin -blue, 
instead  of  the  cornflower-blue  of  the  sapphire.  The  sapphire,  however, 
exhibits  nearly  the  same  color  throughout,  while  a  cut  stone  of  iolite, 
if  blue  in  one  direction,  will  be  seen  on  turning  to  be  gray  in  another. 
On  this  account,  and  by  reason  of  its  inferior  hardness,  it  is  not  prized 
as  highly  as  the  sapphire,  and  it  has  but  a  limited  use.  The  hardness  of 
iolite  is  somewhat  higher  than  that  of  quartz,  being  from  7-7.5.  Its 
specific  gravity  is  nearly  similar  to  that  of  the  latter  mineral,  being  2.6 
to  2.66.  In  composition  it  is  a  hydrous  silicate  of  alumina,  magnesia,  and 
iron.  It  is  barely  fusible  before  the  blowpipe,  and  is  not  attacked  by 
acids.  Its  luster  is  vitreous,  and  its  color  may  be  imitated  in  glass; 
but  the  strong  dichroism  of  the  native  mineral  cannot  be  copied.  It 
crystallizes  in  the  orthorhombic  system ;  but  clear,  transparent  crystals 
are  rare,  the  strong  tendency  of  the  mineral  to  alter  on  exposure  caus- 
ing them  to  become  clouded  and  opaque.  Pieces  available  for  cutting 
occur  generally  as  grains  in  granite,  or  gneiss,  or  as  rolled  pebbles  in 
the  beds  of  streams.  /The  finest  of  the  latter  come  from  Ceylon,  and 
this  is  the  source  of  most  of  the  iolite  used  in  jewelry/  It  occurs 
similarly  in  Brazil,  associated  with  topaz  in  stream  gravels.  Good  iolite 
for  cutting  has  been  obtained  from  granite  in  Haddam  and  Guilford, 
Connecticut,  in  this  country.  Besides  blue,  iolite  may  also  present 
colors  of  yellow,  green,  or  brown.  Only  the  blue  is  cut,  however, 
and  the  cutting  is  made  so  as  to  show  this  color  at  the  surface.  It 
is  usually  given  the  table,  or  step  cut,  but  sometimes  the  cabochon, 
especially  if,  as  is  sometimes  the  case,  a  star-like  effect,  like  that  of 
the  star  sapphire,  can  be  obtained. 

136 


RUTILE 

This  mineral  has  luster,  hardness,  and  power  of  resistance  to  solvents 
sufficient  to  fit  it  for  use  as  a  gem,  but  ordinarily  lacks  transparency 
and  brilliancy  of  color.  Rutile  is  oxide  of  titanium,  containing  more 
or  less  iron.  Its  usual  color  is  reddish-brown,  passing  into  black  with 
a  higher  content  of  iron.  The  latter  variety,  known  as  nigrine,  gives, 
when  cut,  a  stone  closely  resembling  the  black  diamond  in  appearance. 
The  luster  of  rutile  is  adamantine,  like  that  of  the  diamond ;  but  owing 
to  its  being  rather  opaque,  its  luster  usually  borders  on  the  metallic 
also.  It  is  rarely  sufficiently  transparent  to  make  clear 
stones  of  any  considerable  size.  At  times,  however,  pieces 
are  found  which  cut  into  gems  almost  like  the  ruby. 
Rutile  is  the  mineral  which  usually  forms  the  hair-like 
crystals  penetrating  quartz  and  other  minerals,  and  these 
often  have  a  blood-red  color.  The  hardness  of  rutile 
is  6-6.5.  Its  specific  gravity  is  high,  often  enabling  one 
to  recognize  it  by  simply  taking  it  in  the  hand.  It  equals 
4.2.  Rutile  is  infusible  before  the  blowpipe,  and  is  unattacked  by  acids. 

What  are  perhaps  the  finest  rutile  crystals  known  in  the  world 
come  from  Graves  Mountain,  Georgia.  Here  long,  splendent  crystals 
are  obtained,  which  are  objects  of  sufficient  beauty  to  be  worn  uncut. 
It  is  characteristic  of  rutile  to  form  groups  of  crystals,  each  meeting 
the  other  at  an  angle,  so  as  to  form  a  complete  polygon.  These  objects 
make  natural  ornaments  also. 

Rutile  crystallizes  in  the  tetragonal  system.  The  cut  stones  are 
usually  given  the  form  of  brilliants. 


137 


TITANITE 

(SPHENE) 

Titanite  is  one  of  the  few  minerals  which  possess,  like  diamond,  an 
adamantine  luster.  This  luster  gives  to  gems  cut  from  titanite  a  rich 
effect,  but  they  lack  depth  of  color  and  hardness  sufficient  to  make  them 
stones  of  the  first  rank. 

Titanite  occurs  in  numerous  colors,  brown,  yellow,  and  green  being 
the  most  common  and  characteristic.  Stones  cut  from  these  are  usually 
distinctly  -pleochroic,  showing  red  and  yellow  in  different  directions, 
while  in  one  direction  they  may  be  colorless.  Only 
the  transparent  pieces  are  cut  for  gems.  They 
resemble  chrysoberyl,  topaz,  garnet,  or  chrysolite,  in 
appearance.  Their  hardness  is  5  to  5^,  somewhat 
below  that  essential  for  a  good  wearing  gem.  The 
S  hene  specific  gravity  of  titanite  is  3.4  to  3.55.  In  compo- 

sition it  is  a  titano-silicate  of  calcium,  the  percent- 
ages being,  silica  30.6,  titanium  dioxide  40.8,  lime  28.6.  It  is 
fusible  before  the  blowpipe  to  a  colored  glass.  It  is  attacked  by  sul- 
phuric and  hydrofluoric  acid.  It  crystallizes  in  the  monoclinic  system, 
the  crystals  often  having  the  shape  of  a  wedge,  whence  the  name  sphene, 
from  the  Greek  sphen,  a  wedge,  by  which  the  mineral  is  often  known. 

The  finest  transparent  crystals  of  titanite  come  from  Switzerland, 
being  generally  of  a  yellowish-green  color.  Kunz  mentions  crystals  of 
titanite  from  Bridgewater,  Bucks  County,  Pennsylvania,  over  an  inch  in 
length,  which  afford  fine  greenish-yellow  or  golden  stones,  weighing  10 
to  20  carats. 


138 


AXINITE 

This  is  a  mineral  occasionally  cut  for  gem  purposes,  but  not  exten- 
sively in  vogue.    It  furnishes  a  stone  of  a  clove-brown  color,  transparent, 
and  with  glossy  luster.    It  is  somewhat  deficient  in  hardness,  being  softer 
than  quartz,  though  harder  than  feldspar.    Hardness  6.5-7.    Before  the 
blowpipe  axinite  fuses  readily,  giving  a  pale  green  flame.     It  is  not 
attacked  by  acids.     In  composition   it  is  a  boro-silicate 
of  aluminum  and  calcium,  with  varying  amounts  of  iron 
and  manganese.      Besides  occurring  of   brown  color,  it 
may  also  be  of  blue,  gray,   or   yellow  shades,  although 
brown  is  the  most  common.      Like  epidote,  iolite,  tour- 
maline, etc.,  axinite  is  strongly  pleochroic,  showing  olive- 
green,  cinnamon-brown,  and  violet-blue  in  different  direc-         Axinite 
tions,  especially  if   examined  with  the  dichroscope.     It 
crystallizes  in  the  triclinic  system,  usually  in  thin,  broad  blades,  which  so 
much  resemble  an  ax  that  they  have  given  the  name  of  axinite  to  the 
mineral. 

^/The  best  known  occurrence  of  axinite,  and  that  which  yields  the 
finest  crystals,  is  near  Bourg  d'Oisans,  Dauphine,  France.  It  occurs  here 
with  albite,  prehnite,  and  quartz.  /  There  are  several  other  occurrences 
of  the  mineral  in  Europe  and  the  United  States,  but  few  yield  material 
of  sufficient  size  and  transparency  for  cutting. 


139 


The  species  above  named  form  a  group  of  black,  heavy  minerals, 
with  pitchy  or  sub-metallic  luster,  which  are  occasionally  cut  when  a- 
brilliant  black  gem  is  desired.  They  are  peculiar  in  their  composition 
in  that  they  are  salts  of  the  rare  earths,  yttrium,  cerium,  tungsten 
niobium,  etc.  They  are  therefore  often  known  as  rare  earth  minerals. 
They  have  a  hardness  of  5-6,  and  a  specific  gravity  of  5-6.  The  latter 
is  sufficient  to  distinguish  them  from  any  other  of  the  black  minerals 
used  in  jewelry,  such  as  jet  and  obsidian,  the  difference  being  at  once 
noticeable  on  taking  one  of  either  in  the  hand.  Their  color  being  a  rich 
velvet  black,  and  their  luster  brilliant,  they  are  superior  in  appearance 
to  the  more  extensively  used  black  minerals,  and  should  have  a  wider 
vogue.  Samarskite  is  perhaps  the  richest  in  color  and  luster  of  any  of 
the  series,  this  being  a  deep  velvety  black.  The  minerals  are  found  in 
this  country  chiefly  in  North  Carolina,  although  allanite  is  obtained  also 
in  Virginia  and  Texas.  In  Europe  they  are  found  in  Norway  and  the 
Ural  Mountains. 


140 


Rutilated  Quartz,  polished  (Brazil). 
Rose  Quartz,  polished  (Black  Hills). 


461 


QUARTZ  (crystalline). 
Smoky  Quartz  (Switzerland). 


IOS,   ir   «.   w.   MUKFtmO,   CH 


Amethyst  (Virginia). 
Amethyst  (Montana). 


QUARTZ 

This  is  the  most  abundant  of  common  minerals,  and  one  which  appears 
in  a  great  variety  of  colors  and  structures  looking  very  unlike.  In  color, 
hardness,  transparency,  and  luster  many  of  these  varieties  of  quartz  are 
well  suited  for  use  as  gems,  but  owing  to  their  common  occurrence  they 
are  less  highly  valued  than  other  minerals  possessing  perhaps  no  more 
desirable  qualities.  Nevertheless  the  varieties  of  quartz  have  an  extensive 
use  in  jewelry,  and  deserve  description  in  detail.  The  chemical  composi- 
tion of  all  varieties  of  quartz  is  the  same,  viz.,  oxide  of  silicon.  The 
physical  characters  are  likewise  nearly  constant,  and  are  as  follows :  hard- 
ness, 7;  specific  gravity,  2.65;  cleavage,  none;  fracture,  conchoidal; 
infusible  before  the  blowpipe;  insoluble  in  common  acids. 

The  varieties  of  quartz  fall  naturally  into  two  groups,  the  pheno- 
crystalline  (plainly  crystalline),  and  cryptocrystalline  (obscurely  crystal- 
line). Of  these  the  phenocrystalline  varieties  will  be  considered  first. 
These  include  rock  crystal,  amethyst,  smoky  quartz,  rose  quartz,  and 
sagenitic  quartz,  with  others  of  minor  importance.  The  differences 
between  these  varieties  are  almost  wholly  differences  of  color. 

Rock  Crystal.  This  is  quartz  in  its  purest  form.  Typically  it  is  trans- 
parent and  colorless,  but  clouded  and  opaque  occurrences  are  included 
under  this  head.  By  the  ancients  it  was  supposed  to  be  petrified  ice,  and 
hence  the  Greeks  applied  it  to  their  word  for  ice,  from  which  we  get  our 
word  crystal.  One  reason  for  this  belief  was  the  fact  that  much  of  the 
quartz  known  to  them  came  from  the  high  peaks  of  the  Alps.  They  con- 
cluded therefore  that  it  was  ice  frozen  so  hard  it  could  not  melt.  This 
belief  must  have  survived  nearly  to  modern  times,  for  in  1676  Robert 
Boyle,  the  eminent  physicist,  thought  it  necessary  to  bring  forward  several 
arguments  to  prove  the  falsity  of  the  idea.  One  of  these  arguments  was 
that  quartz  was  two  and  a  half  times  as  heavy  as  water,  and  another 
that  it  was  found  in  tropical  countries. 

Quartz  in  the  form  of  rock  crystal  is  now  known  to  occur  in  all  parts 
of  the  globe,  although  the  occurrences  of  clear,  transparent  rock  crystal 
suitable  for  cutting  are  comparatively  few  in  number.  Rock  crystal  is 
frequently,  though  not  always,  found  in  the  form  of  terminated  crystals, 
having  usually  the  shape  of  six-sided  prisms  capped  at  one  or  both  ends 

141 


by  pyramids.  For  use  in  jewelry  or  for  purposes  of  ornament  rock 
crystal  is  cut,  the  form  of  cutting  depending  on  the  size  of  pieces  that 
can  be  obtained  clear. L  The  favorite  use  for  the  largest  pieces  is  to  cut 
them  into  spheres  or  balls.  This  was  done  even  in  the  times  of  the 
Romans,  the  aristocratic  ladies  of  that  day  carrying  the  spheres  in 
summer  for  the  sake  of  the  coolness  they  afforded.  The  same  custom 
prevails  among  the  Japanese  at  the  present  time,  and  the  industry  of 
making  the  balls  is  extensively  carried  on  in  Japan.  Balls  from  four  to 
six  inches  in  diameter  have  a  high  value,  both  on  account  of  the  rarity  of 
finding  so  large,  transparent  and  flawless  pieces  of  quartz  and  because 
of  the  labor  of  making  them//  The  smaller  balls  are  somewhat  in  fashion 


Forms  of  quartz  crystals 

in  Europe  and  America  at  the  present  time  as  fortune  tellers,  the  images 
of  objects  seen  through  the  spheres  being  supposed,  according  to  a  fancy 
which  has  survived  from  an  early  period,  to  indicate  the  observer's  future. 

A  superb  example  of  carving  in  rock  crystal  is  to  be  seen  in  the 
Morgan  collection  of  gems  in  the  American  Museum  of  Natural  History 
of  New  York  City.  This  object  is  a  globe  four  inches  in  diameter,  on 
which  are  outlined  the  continents  and  oceans,  while  a  figure  of  Atlas 
beneath  supports  the  sphere. 

Rock  crystal  is  also  cut  into  seals,  paper-weights,  and  other  orna- 
mental objects,  and  the  small  pieces  are  used  in  enormous  quantities  for 
cutting  into  stones  for  rings,  pins,  brooches,  etc.  These  are  often  known 
as  "  rhinestones,"  but  also  as  "Lake  George  diamonds,"  "Brazilian 
diamonds,"  and  "diamonds"  from  whatever  locality  they  come.  These 
make  desirable  stones  as  far  as  durablity  is  concerned,  and  are  fairly 
brilliant,  but  are  not  to  be  compared  with  the  diamond  in  high 
refractive  powers.  An  attempt  to  pass  off  a  rhinestone  for  a  dia- 
mond can  be  easily  detected  by  the  relative  softness  of  the  former,  it 
being  possible  to  scratch  it  not  only  with  diamond  but  also  with  corun- 
dum or  topaz.  Rhinestones  have  little  intrinsic  value  owing  to  the 
common  occurrence  of  the  raw  material.  They  do  not  therefore  legiti- 

142 


mately  bring  a  price  much  beyond  that  of  the  labor  of  cutting,  which  is 
at  present  from  a  dollar  and  a  half  to  two  dollars  a  dozen  for  stones  of 
the  ordinary  sizes.  Considerable  rock  crystal  is  used  for  making  the 
so-called  "pebble"  eye-glasses  and  spectacles.  It  is  a  common  notion 
that  these  are  more  beneficial  to  the  eyes  than  glass.  There  seems  to  be 
no  good  reason  for  this  opinion,  however,  and  unless  the  crystal  is  cut  in 
a  certain  definite  crystallographic  direction,  that  is,  at  right  angles  to  the 
prism,  the  light  coming  through  to  the  eye  of  the  wearer  will  be  broken 
up  by  double  refraction,  and  may  be  positively  harmful  in  its  effects. 

Another  occasional  use  to  which  rock  crystal  is  put  is  for  making 
mirrors,  for  which  purpose  it  is  said  to  be  superior  to  glass  in  that  it 
does  not  detract  from  the  rosiness  of  the  complexion. 

The  chief  source  of  the  rock  crystal  used  in  the  arts  at  the  present 
time  is  Brazil.  In  several  provinces  of  that  country,  but  especially  those 
of  Minas  Geraes  and  Goyaz,  large,  clear  masses,  often  in  the  form  of 
crystals,  are  found  loose  in  the  soil.  These  are  picked  up  and  shipped  to 
various  markets,  furnishing  a  supply  of  excellent  material  at  small  cost. 
In  India  considerable  rock  crystal  is  obtained  from  localities  in  the 
government  of  Madras,  and  fashioned  by  the  natives  into  various 
objects. 

The  French  and  Swiss  Alps,  which  probably  furnished  the  raw  mate- 
rial to  the  Romans,  still  afford  a  small  supply,  of  which  limited  use  is 
made.  Quartz  pebbles,  derived  doubtless  from  these  Alpine  sources,  are 
found  in  the  bed  of  the  Rhine  and  its  tributaries,  and  it  was  to  these  when 
cut  that  the  name  of  rhinestones  was  originally  applied. 

The  Island  of  Madagascar  has  since  the  middle  of  the  seventeenth 
century  been  noted  for  the  large  masses  of  clear  quartz  to  be  obtained 
there.  The  quartz  is  found  mostly  in  stream  beds  in  the  form  of  rolled 
masses,  but  also  occurs  in  crystals.  Single  pieces  are  found  weighing 
several  hundred  pounds.  The  Madagascar  quartz  furnishes  the  material 
for  most  of  the  crystal  balls  sold  as  Japanese,  many  of  these  being  not 
even  cut  in  Japan.  In  our  own  country  several  localities  afford  clear 
quartz  crystals,  the  best  known  being  Hot  Springs,  Arkansas,  and  Little 
Falls,  New  York.  Those  from  the  latter  locality  are  doubly  terminated, 
and  are  sold  quite  extensively  in  their  natural  shape  for  jewels,  as  they 
are  small  and  brilliant. 

The  ancients  prized  rock  crystal  much  more  highly  than  we  do, 
because  it  answered  them  many  of  the  purposes  for  which  we  now 
find  glass  cheaper  and  more  suitable.  Wine-glasses  were  made  from 
it,  though  at  great  cost,  a  thousand  dollars  being  considered  a  small 
price  for  one.  Lenses  of  rock  crystal  were  used  to  concentrate  the 

143 


rays  of  the  sun  to  procure  heat  for  cauterizing  wounds  and  to  light 
fires,  especially  sacrificial  ones. 

The  following  lines,  adopted  from  an  early  Roman  writer,  refer 
to  the  latter  custom : 

"Take  in  thy  pious  hand  the  Crystal  bright, 
Translucent  image  of  the  Eternal  Light; 
Pleased  with  its  luster,  every  power  divine 
Shall  grant  thy  vows  presented  at  their  shrine; 
But  how  to  prove  the  virtue  of  the  stone, 
A  certain  mode  I  will  to  thee  make  known: 
To  kindle  without  fire  the  sacred  blaze, 
This  wondrous  gem  on  splintered  pine-wood  place, 
Forthwith,  reflecting  the  bright  orb  of  day, 
Upon  the  wood  it  shoots  a  slender  ray  • 
Caught  by  the  unctuous  fuel  this  will  raise 
First  smoke,  then  sparkles,  then  a  mighty  blaze: 
Such  we  the  fire  of  ancient  Vesta  name, 
Loved  by  th'  immortals  all,  a  holy  flame; 
No  other  fire  with  such  grateful  fumes 
The  fatted  victim  on  their  hearths  consumes; 
Yet  though  of  flame  the  cause,  strange  to  be  told, 
The  stone  snatched  from  the  blaze  is  icy  cold." 

Globes  of  rock  crystal  were  found  among  the  ruins  at  Nineveh, 
showing  that  the  mineral  was  prized  by  that  people.  The  Venetians 
carried  the  art  of  engraving  on  rock  crystal  to  a  high  degree  of  per- 
fection, the  effect  of  the  figures  being  greatly  enhanced  by  the  addi- 
tion of  foils  of  different  colors.  Rock  crystal  was  also  formerly  stained 
many  different  colors  to  imitate  other  gems.  The  staining  was  per- 
formed by  heating  the  stones  to  redness  and  immersing  them  in  a  dye 
possessing  the  desired  color.  The  sudden  change  of  temperature  causes 
minute  cracks  over  the  surface,  imperceptible  to  the  naked  eye,  which 
absorb  the  coloring  matter,  and  give  the  effect  of  complete  coloration. 

The  use  of  quartz  balls  for  divination  has  already  been  referred 
to.  Rock  crystal  has  also  long  been  credited  with  curative  powers, 
especially  of  hemorrhage  and  dysentery.  To  cure  the  former  it  is 
applied  to  the  bleeding  part,  and  to  cure  the  latter  the  powder  mixed 
with  wine  is  drunk.  It  has  also  been  regarded  a  cure  for  headache  and 
faintness  if  held  in  the  mouth.  In  parts  of  Virginia  it  is  supposed  to  be 
a  cure  for  sties,  the  sty  being  rubbed  with  the  crystal  three  times 
a  day  for  three  days. 

Many  of  the  tribes  of  the  North  American  Indians  use  pieces  of  rock 
crystal  in  their  ceremonies,  and  regard  them  as  having  special  magical 
powers. 

144 


The  Hindoos  regard  rock  crystal  a  specific  for  consumption,  leprosy, 
and  poisoning.  It  is  known  among  them  as  "unripe  diamond,"  and 
may  be  substituted  in  medicine  for  diamond. 

Amethyst.  This  term  is  applied  to  the  violet  or  purple  varieties 
of  quartz.  It  is  derived  from  two  Greek  words  meaning  "  not  to  inebri- 
ate," and  indicates  the  belief  of  the  ancients  that  wine  dr^nk  from 
cups  made  of  this  mineral  could  never  have  any  deleterious  effect. 
All  degrees  of  color  are  to  be  found  in  amethyst,  from  that  only 
slightly  tinted  to  that  so  dark  as  to  be  almost  opaque.  The  color 
may  be  irregularly  distributed,  being  sometimes  in  spots  and  again 
shading  uniformly  in  the  same  crystal  from  light  to  dark.  Of  these 
colors  the  dark  reddish-purple  is  the  most  highly  esteemed,  the  paler 
stones  being  less  sought  after.  A  reason  for  this  is  to  be  found  in  the 
fact  that  by  artificial  light,  especially  if  this  contains  yellow  rays,  pale 
stones  lose  their  violet  color  and  become  a  dull  gray.  The  deeply 
colored  amethysts,  however,  especially  such  as  have  been  found  in 
Maine,  change  to  a  wine  color  by  artificial  light,  and  thus  their  beauty 
is  enhanced.  Besides  being  of  a  deep  purple  color,  a  good  amethyst 
should  be  perfectly  transparent  and  uniform  in  hue  throughout.  The 
nature  of  the  coloring  matter  of  amethyst  is  not  known.  For  a  long 
time  it  was  thought  to  be  oxide  of  manganese;  but  as  the  color  disap- 
pears on  heating  it  is  now  believed  to  be  a  form  of  organic  matter. 
It  has  been  noticed  in  some  places  where  amethyst  is  mined  that  the 
most  deeply  colored  stones  are  at  the  surface,  and  that  their  color 
grows  paler  as  the  vein  is  followed  downward.  The  cause  of  this 
phenomenon  is  not  known.  By  partial  heating  the  color  of  amethyst 
can  be  changed  to  yellow,  and  some  of  the  so-called  citrine  is  made 
in  this  way. 

Much  opaque  and  coarse  quartz  has  an  amethystine  color,  but  such 
is  obviously  of  no  value  for  gem  purposes.  The  chief  supply  of  the 
amethysts  used  for  jewelry  at  the  present  time  comes  from  Siberia 
and  Brazil.  ^The  Siberian  mines  are  located  in  the  Urals  in  the  vicin- 
ity of  Mursinka  and  Alabashka.  The  amethyst  occurs  in  cavities  in 
granite,  accompanied  by  beryl  and  topaz.  Much  of  it  is  near  the  sur- 
face, and  it  is  also  found  lying  loose.'  The  Brazilian  amethysts  occur 
partly  in  cavities  in  a  black  eruptive  rock  (melaphyre),  and  partly 
as  pebbles  in  the  river  gravels,  accompanied  by  chrysoberyl,  topaz,  etc. 
Amethyst  of  gem  quality  is  also  found  in  Ceylon  in  gem  gravels. 

In  our  own  country  amethyst  occurs  abundantly,  but  not  often  of  the 
best  quality  for  cutting.  Some  of  the  finest  amethyst  known  has  come 
from  Oxford  County,  Maine,  but  only  a  few  specimens  have  thus  far 

145 


been  obtained.  Delaware  and  Chester  counties,  Pennsylvania,  have 
furnished  good  amethysts,  as  well  as  Haywood  County,  North  Caro- 
lina. One  of  the  best  known  localities  for  amethyst  in  America  is 
Thunder  Bay,  on  the  north  shore  of  Lake  Superior.  Crystallized  ame- 
thyst is  found  here  in  large  quantities  coating  veins  in  the  rock. 
While  many  of  the  crystals  are  highly  colored  they  are  not  uniform 
in  color  and  lack  clearness,  so  that  few  good  gems  have  been  obtained 
here. 

Amethyst  was  much  more  highly  prized  in  former  times  than  now, 
probably  on  account  of  its  greater  scarcity  then.  A  celebrated  amethyst 
necklace,  owned  by  Queen  Charlotte,  of  England,  which  was  valued  at 
the  time  it  was  made  at  $10,000,  would  probably  be  worth  hardly  $500 
now.  In  spite  of  the  comparative  abundance  of  amethyst  at  the  present 
time  there  is  a  constant  demand  for  good  stones,  since  no  other  gem 
affords  its  charming  violet  color.  One  dollar  a  carat  is  an  average 
price  for  amethyst  at  the  present  day,  and  this  value  remains  about 
the  same  even  with  an  increase  in  size  of  the  stones,  as  large  amethysts 
are  comparatively  common.  The  step  cut  is  usually  adopted  for  ame- 
thyst, and  is  well  •  adapted  to  it.  Brilliants  are,  however,  common, 
and  the  mixed  cut  also  often  gives  a  good  effect.  Amethyst  was 
often  worn  in  the  Middle  Ages  as  an  amulet  and  preserver  of  the 
wearer  in  battle.  It  was  supposed  to  be  serviceable  to  persons  having 
petitions  to  make  to  princes,  and  to  be  a  preventive  of  hailstorms  and 
locusts.  It  has  also  long  figured  as  a  pious  or  episcopal  gem,  being  the 
stone  which  is  regarded  as  imparting  especial  dignity  or  beauty  to  the 
property  of  the  church.  It  is  a  gem  especially  sacred  to  St.  Valentine, 
he  being  said  always  to  have  worn  one. 

Rose  Quartz.  This  form  of  quartz,  the  color  of  which  is  indicated 
by  its  name,  is  rarely  of  sufficient  transparency  to  be  prized  as  a  gem. 
Cut,  however,  into  various  ornaments,  it  makes  objects  of  considerable 
beauty.  Its  luster,  instead  of  being  glassy  like  that  of  other  forms  of 
quartz,  is  nearly  always  more  or  less  greasy.  The  ingredient  which 
gives  it  color  is  not  known.  *  It  is  probably  some  organic  matter,  since 
the  color  disappears  on  heating  and,  unfortunately  for  the  extended  use 
of  the  stone,  often  fades  considerably  on  exposure  to  light.  Unlike 
other  varieties  of  pheno-crystalline  quartz,  rose  quartz  has  never  yet 
been  found  in  the  form  of  distinct  crystals.  There  are  numerous  locali- 
ties whence  rose  quartz  of  good  color  may  be  obtained,  although  it  is  not 
of  so  common  occurrence  as  most  other  varieties  of  quartz.  The  best 
rose  quartz  in  this  country  comes  from  Oxford  County,  Maine,  and  the 
Black  Hills.  Foreign  localities  are  the  Urals,  Brazil,  and  Ceylon. 

146 


Smoky  Quartz.  This  variety  of  quartz  is  often  known  as  "  smoky 
topaz,"  a  misleading  term,  since  the  mineral  is  not  topaz.  As  its 
name  implies,  its  color  is  like  that  of  smoked  glass,  all  gradations  occur- 
ring between  a  mere  tinge  to  color  so  dark  as  to  render  the  mineral 
practically  opaque.  The  color  often  varies  considerably  in  the  same 
crystal,  being  darker  and  lighter  in  spots.  The  coloring  matter  is 
undoubtedly  carbonaceous  and  organic  in  nature,  for  when  a  crystal  is 
heated  it  gives  off  a  smell  of  burning  organic  matter,  and  by  heating  for 
some  length  of  time  the  coloring  may  be  entirely  burned  out.  At  an 
intermediate  stage  in  such  heating  the  color  becomes  brown  or  yellow, 
and  stones  of  this  color  are  often  cut  as  gems,  and  known  by  the  name 
of  "Spanish  topaz"  or  "citrine."  True  citrine  is,  however,  transparent 
quartz  with  a  natural  yellow  color.  The  most  remarkable  crystals  of 
smoky  quartz  known  are  some  that  were  found  in  1868  in  a  hollow  in 
granite  in  a  locality  in  the  Canton  Uri,  Switzerland.  About  three  thou- 
sand pounds  of  well-formed  crystals  were  there  found,  the  largest  and 
best  of  which  are  preserved  in  the  Berne  Museum.  The  same  region, 
and  neighboring  ones  in  the  Alps,  have  also  furnished  large  quantities 
of  smaller  crystals  of  notable  perfection  in  form,  and  of  fine  quality. 

The  next  most  important  locality  for  smoky  quartz  is  in  the  vicinity 
of  Pike's  Peak  in  the  State  of  Colorado.  Here  the  smoky  quartz  occurs 
in  pockets  in  a  coarse  pegmatite  accompanying  amazon  stone  and  other 
feldspars.  Kunz  mentions  one  crystal  from  this  locality  which  measured 
four  feet  in  length.  Large,  flawless  pieces  have  been  found,  which  have 
been  cut  into  facetted  stones  weighing  a  pound  or  more.  Alexander 
County,  North  Carolina,  has  also  furnished  much  excellent  smoky  quartz. 
Large  clear  crystals  and  masses  have  been  found  at  Auburn,  Maine,  one 
of  these  crystals  being  nearly  two  feet  in  length.  These  have  furnished 
material  for  balls  and  other  objects.  Smoky  quartz  is  sometimes  known 
by  the  name  of  cairngorm  stone,  from  its  occurrence  at  Cairngorum, 
near  Banff,  in  northern  Scotland.  The  quartz  from  this  locality  was 
at  one  time  widely  distributed,  and  came  to  be  regarded  as  the  national 
gem  of  Scotland.  The  cairngorm  stone  occurs  in  connection  with  masses 
of  granite,  and  is  obtained  by  digging  shallow  pits  or  trenches  in  areas 
where  considerable  decomposition  has  taken  place.  The  stone  as  used  in 
jewelry  is  usually  heated  to  give  it  a  yellow  color.  Little  of  it  is  mined 
at  the  present  time. 

Smoky  quartz  has  the  physical  and  chemical  properties  of  rock  crys- 
tal, by  which  it  can  be  distinguished  from  other  brown  gems,  such  as 
axinite  or  brown  diamond.  It  is  usually  cut  in  the  form  of  the  brilliant 
or  the  step  cut.  Being  available  in  large,  clear  pieces,  it  is  also  used  for 

147 


seals,  brooches,  penholders,  etc.  It  exceeds  rock  crystal  little  if  any 
in  market  price. 

Sagenitic  Quartz.  This  form  of  quartz  is  variously  known  as  "  sage- 
nite,"  "fleche  d'amour"  (love's  arrow),  "hair  stone,"  "needle  stone," 
and  if  the  included  mineral  be  rutile,  "  rutilated  quartz."  These  terms 
all  refer  to  colorless  crystallized  quartz  which  is  penetrated  by  hair-like 
crystals  of  other  minerals.  An  illustration  of  the  occurrence  is  given 
in  the  accompanying  colored  plate.  Of  the  minerals  so  included  rutile 
is  the  most  common,  but  tourmaline,  hornblende,  epidote,  goethite,  and 
others  occur.  The  inclusions  have  doubtless  been  formed  in  the  quartz 
by  crystallizing  at  the  same  time  with  it,  the  quartz  in  this  case  being 
the  "host."  The  length  of  the  included  crystals  may  be  considerable. 
Some  of  the  rutilated  quartz  from  Madagascar  has  single  included  crys- 
tals six  inches  long.  The  quantity  of  the  included  mineral  may  vary 
from  a  few  long,  scattered  individual  crystals  to  a  multitude  of  short 
ones.  For  cut  stones,  pieces  of  the  latter  sort  are  usually  preferred. 
Some  of  the  prettiest  effects  are  produced  when  the  included  mineral  is 
rutile,  and  is  sufficiently  transparent  to  be  of  a  blood-red  color  by  trans- 
mitted light.  By  cutting  suitable  pieces  of  this  sort  into  the  form  of 
hearts,  the  effect  indicated  by  the  term  "love's  arrow"  can  be  prettily 
obtained.  Often  the  included  crystals  cross  each  other  nearly  at  right 
angles,  thus  giving  the  appearance  of  a  network.  It  is  on  account 
of  this  appearance  that  the  name  sagenite,  from  the  Greek  sagene,  a  net, 
is  given.  Sagenitic  quartz  is  obtained  in  various  localities.  Madagascar 
is  perhaps  the  chief  source  of  supply  at  the  present  time,  much  excellent 
material  being  obtained  there.  The  rock  crystal  of  Brazil  is  frequently 
sagenitic  also.  Several  localities  in  the  United  States  furnish  sagenitic 
quartz,  among  them  being  North  Carolina,  Rhode  Island,  and  California. 
Perhaps  the  finest  specimens  ever  seen  were  gotten  from  some  boulders 
found  in  the  vicinity  of  Hanover,  New  Hampshire,  in  the  years  1830- 
1850.  Crystals  of  quartz  containing  hair-like  crystals,  or  massive  o:- 
scale-like  inclusions  of  chlorite,  are  obtained  in  Japan,  which  are  pre- 
pared for  ornamental  purposes  simply  by  smoothing  and  polishing  the 
natural  crystal  surfaces. 

"  Cat's-eye"  "  Tiger-eye."  These  are  forms  of  quartz  containing 
fibrous  inclusions,  which,  instead  of  being  scattered,  are  massed  together, 
so  that  upon  a  polished  surface  a  sheen  like  that  of  silk  is  seen  by 
reflected  light.  The  term  of  Occidental  cat's-eye  is  often  applied  to 
cat's-eye  of  this  sort,  in  distinction  from  the  Oriental  cat's-eye  com- 
posed of  chrysoberyl.  "  Tiger-eye "  is  made  up  of  somewhat  coarser 
fibers  than  cat's-eye.  It  is  of  a  golden  yellow  color,  while  the  color  of 

148 


cat's-eye  varies  from  pale  blue  and  pale  green  to  reddish-brown.  A  blue 
variety  occurring  with  the  South  African  tiger-eye  is  known  as  "  hawk's- 
eye."  A  piece  of  either  of  these  minerals  if  cut  en  cabochon  in  a  proper 
manner  exhibits  a  band  of  light  across  it,  changing  in  position  when  the 
stone  is  turned.  The  included  fibrous  mineral  which  gives  the  effect  is 
asbestos.  In  the  tiger-eye  obtained  from  South  Africa  all  gradations  are 
found  between  crocidolite,  which  is  a  fibrous  form  of  amphibole,  and 
quartz,  the  tiger-eye  being  formed  by  a  replacement  of  the  crocidolite 
by  the  quartz.  Thus  the  structure  of  the  crocidolite  is  retained,  but 
the  stone  has  the  hardness  and  luster  of  quartz. 

Cat's-eye  comes  chiefly  from  Asia,  the  Malabar  Coast  of  India  and 
the  Island  of  Ceylon  being  the  localities  most  prolific  in  it.  In  the  latter 
locality  it  accompanies  the  Oriental  or  chrysoberyl  cat's-eye.  It  is,  how- 
ever, much  less  valuable  than  the  latter. 

^Nearly  all  the  tiger-eye  used  at  the  present  time  comes  from  South 
Africa.  It  is  found  in  a  range  of  quartzose  schists  called  the  Asbestos 
Mountains,  located  in  Griqualand,  and  extending  from  Griquatown  in  a 
northeasterly  direction  toward  the  Transvaal.  Griquatown  is  about  one 
hundred  miles  west  of  Kimberley.  Other  localities  northward  along 
the  Orange  River  also  furnish  tiger-eye.  The  mineral  as  found  varies 
in  color  from  blue  to  yellow,  according  to  the  degree  of  oxidation  of 
the  iron  of  the  mineral.  As  already  noted,  the  blue  is  called  hawk's- 
eye.  Owing  to  the  quantity  of  the  raw  material  available  tiger-eye  brings 
a  low  price,  and  has  dropped  out  of  fashion  to  a  considerable  extent. 
Twenty-five  years  ago  it  commanded  a  price  of  $6  a  carat,  being  rated  as 
high  as  turquois  at  the  present  day.  Owing  to  the  competition  of  two 
dealers  at  that  time  and  the  appearance  of  an  immense  supply,  the  price 
quickly  fell  to  less  than  twenty-five  cents  per  pound,  and  the  demand 
for  it  almost  ceased. ^ 

The  cutting  of  tiger-eye  is  now  largely  carried  on  in  Oberstein  and 
vicinity  at  the  great  agate-cutting  establishments.  Ring  and  brooch 
stones,  dishes,  and  vases  are  some  of  the  objects  made  from  it. 

Aventurine.  Quartz  known  by  this  name  contains  inclusions,  not 
in  the  form  of  fibers,  but  in  that  of  scales  of  some  bright  mineral,  such 
as  mica  or  hematite.  The  quartz  thus  presents  a  spangled  appearance. 
The  spangles,  according  to  the  size  of  the  included  scales,  may  be 
coarse  or  fine.  The  choicest  aventurine  is  that  in  which  each  scale 
gives  a  distinct  reflection.  The  quartz  base  may  be  brown,  red,  yellow, 
or  black,  or  rarely  bluish  or  greenish  in  color,  and  the  spangles  usually 
silvery  or  golden.  The  aventurine  most  commonly  used  is  of  a  reddish 
yellow  color  with  a  coppery  sheen.  Aventurine  quartz  resembles  the 

149 


form  of  feldspar  known  as  sunstone  in  appearance,  but  can  easily 
be  distinguished  from  it  by  its  greater  hardness. 

The  best  known  localities  for  aventurine  at  the  present  time  are 
the  Ural  and  Altai  mountains  in  Russia.  In  the  former  it  occurs  in 
the  vicinity  of  Slatoust,  in  strata  of  mica  schist,  and  in  the  latter  not 
far  from  Kolivan.  The  aventurine  from  the  latter  locality  is  cut  into 
large  vases  and  dishes.  One  of  the  finest  of  these  is  to  be  seen  in 
the  Museum  of  Practical  Geology  in  London.  This  vase  was  pre- 
sented by  Nicholas  I.  to  Sir  Roderick  Murchison  in  recognition  of  his 
services  in  investigating  the  geology  of  the  Russian  empire.  Aventurine 
is  said  to  be  highly  regarded  in4"*China,  the  imperial  seal  being  always 
made  from  it.  India  and  several  localities  in  Europe  furnish  aventurine ; 
but  none  of  good  quality  has  as  yet  been  found  in  the  United  States. 
Owing  to  the  facility  with  which  it  can  be  obtained  in  masses  it  is  not 
used  extensively  except  for  making  large  ornamental  objects.  Together 
with  sunstone  it  can  be  quite  successfully  imitated  in  glass. 

Crypto-crystalline  quartz.  The  crypto-crystalline  (obscurely  crystal- 
line) varieties  of  quartz  are  many.  The  following  may  be  named  as  the 
most  important:  Chalcedony,  carnelian,  sard,  chrysoprase,  prase,  plasma, 
bloodstone,  agate,  onyx,  sardonyx,  jasper,  basanite,  flint,  and  hornstone. 
The  distinctions  between  the  different  varieties  are  loose,  and  are  differ- 
ently stated  by  different  authorities.  Some  class  agate,  onyx,  sardonyx, 
plasma,  and  carnelian  as  varieties  of  chalcedony,  while  others  consider 
chalcedony  a  simple  variety. 

The  chalcedonic  varieties  of  quartz  agree  in  having  a  fibrous  struc- 
ture and  in  being  somewhat  softer  (hardness  6^)  and  somewhat  lighter 
(specific  gravity  2.6)  than  crystallized  quartz.  They  also  break  with 
more  difficulty  than  quartz,  being  very  tough.  The  varieties  differ 
among  themselves  chiefly  in  color. 

Chalcedony  has  a  waxy  luster,  and  is  usually  translucent  rather 
than  transparent.  The  transparent  forms  are  known  as  "Oriental," 
the  translucent  as  "  Occidental "  chalcedony.  Common  chalcedony  has 
little  color,  shades  of  gray  and  blue  being  the  most  common,  although 
other  tints  occur.  It  usually  presents  rounded  surfaces  which  have 
grape-like,  kidney-like,  or  stalactitic  forms.  It  occurs  coating  other 
rocks  or  minerals,  or  lines  cavities,  or  fills  veins  and  clefts.  It  is  never, 
so  far  as  known,  deposited  in  any  other  way  than  by  percolating 
waters.  At  Tampa  Bay,  Florida,  the  waters  containing  chalcedony 
have  penetrated  corals  and  preserved  them,  often  giving  forms  show- 
ing the  shape  of  the  coral  outside  and  a  cavity  within.  Throughout 
the  "  Bad  Lands  "  of  the  West,  clefts  in  the  hills  are  often  filled  with 

150 


sheets  of  chalcedony,  varying  in  thickness  from  that  of  thin  paper 
to  nearly  an  inch.  These  chalcedony  veins  ramify  in  all  directions, 
and  often  extend  for  many  rods  without  interruption. 

When  the  chalcedony  is  penetrated  by  branching  forms  of  manganese 
or  iron  oxide,  the  forms  known  as  "  mocha  stones  "  and  "  moss-agates  " 
are  produced.  These  are  not  due  to  vegetation,  any  more  than  the 
similar  forms  of  frost  on  our  window-panes.  Moss-agates  are  found 
in  numerous  localities  in  the  States  of  Utah,  Wyoming,  Colorado,  and 
Montana.  Kunz  remarks  that  "  no  stone  that  is  used  in  jewelry  in  the 
United  States  is  cheaper,  more  beautiful,  or  more  plentiful  than  the 
moss-agate."  The  best  occur  as  rolled  pebbles  in  the  beds  of  streams. 
The  name  "  mocha  stone,"  sometimes  applied  to  moss-agates,  is  either 
due  to  the  fact  that  those  first  used  came  from  Mocha  in  Arabia, 
or  it  is  a  corruption  of  the  word  moss-agate.  The  finest  moss-agates 
now  known  come  from 
India.  A  white  variety  of 
chalcedony,  containing 
minute  blood-red  spots, 
is  known  as  St.  Stephen's 
stone.  Chalcedony  was 
formerly  used  much  more 
and  more  highly  prized 
than  at  the  present  time. 
It  was  especially  employed 
for  seals  and  rings,  but 
also  for  plates,  cups,  and 
vases.  These  were  often 
engraved  in  the  most 
elaborate  manner,  the 

hardness   and    toughness 

.    ,  ,  ,     .  ,, 

oi   the  stone  being   well 

suited  to  this  purpose.  The  sentiment  of  the  stone  is  :  "  A  disperser  of 
melancholy."  The  name  chalcedony  is  from  Chalcedon,  a  city  in  Asia 
Minor,  where  the  original  chalcedony  was  found.  This  mineral  was 
probably  not  like  our  modern  chalcedony,  but  a  green  quartz.  This 
chalcedony  is  mentioned  in  the  Book  of  Revelations  as  one  of  the 
foundation  stones  of  the  Holy  City. 

Carnelian  is  a  red  variety  of  chalcedony;  sard  a  brown  variety. 
All  gradations  between  these  shades  of  course  occur,  those  of  the 
reddish  cast  being  the  most  common.  The  most  highly  prized  color 
for  carnelian  is  a  deep  blood  -red,  appearing  darker  red  in  reflected 

151 


Moss-agate,  India. 


light.  The  lighter  red  and  yellowish  shades  are  less  desirable,  stones 
of  these  shades  being  known  as  "  female  "  carnelians,  while  those  of  the 
darker  shades  are  known  as  "  male "  carnelians.  The  colors  are  due 
to  oxides  of  iron,  and  can  sometimes  be  changed  by  heating.  Thus, 
the  yellowish  and  brownish  carnelians,  being  colored  by  iron  hydroxide, 
can  be  changed  by  heating  to  red,  the  water  being  driven  off  and  iron 
oxide  left.  The  heating  may  be  done  in  the  sun,  or  by  some  other 
slow  means.  Even  olive-green  stones  are  changed  in  India  to  red  by 
this  process.  The  color  may  also  be  introduced  artificially,  by  allowing 
the  stones  to  lie  in  a  mixture  of  metallic  iron  and  nitric  acid,  or  of  iron 
sulphate  for  a  while.  In  this  way  the  iron  salt  needed  for  the  color- 
ing matter  can  be  absorbed  by  the  stone,  and  this  be  changed  after- 
wards to  oxide  by  heating.  The  best  carnelians  come  from  India, 
but  good  stones  are  also  obtained  in  Siberia,  Brazil,  and  Queensland. 
Carnelians  are  cut  usually  in  oval  and  shield-like  shapes.  They  were 
much  employed  by  the  ancients  for  intaglios,  who  believed  them  to 
have  the  power  of  preventing  misfortune,  curing  tumors,  preventing 
hoarseness,  and  strengthening  the  voice.  They  also  insured  victory  in 
all  contests  save  those  of  love.  Used  as  a  powder  or  worn  in  a  ring 
carnelian  was  believed  to  prevent  bleeding  at  the  nose,  and  the  belief 
survives  to  some  extent  to  the  present  day. 

The  name  carnelian  is,  according  to  some  authorities,  derived  from 
the  Latin  word  caro,  carnis,  flesh,  and  refers  to  the  color  of  the  stone ; 
according  to  others,  it  is  from  the  Italian  word  carniola,  which  has  the 
same  meaning. 

Sard,  of  typical  brown  color,  is  much  rarer  than  carnelian,  and 
possesses  a  higher  value.  The  sardius  mentioned  in  the  Bible  as  form- 
ing one  of  the  stones  of  the  high  priest's  breastplate,  was  undoubtedly 
a  carnelian.  The  name  was  derived  from  Sardius,  a  city  of  Lydia, 
whence  fine  carnelians  are  obtained.  Sard  occurs  with  carnelian  and 
grades  into  it.  The  best  sard  should  be  of  a  deep  brown  color,  shading 
to  orange  but  with  a  reddish  tinge  by  transmitted  light.  The  color 
can  be  artificially  produced  by  methods  similar  to  those  described 
below  for  coloring  agates,  but  long  and  careful  treatment  is  required. 
The  sard  was  believed  by  the  ancients  to  confer  cheerfulness  and  cour- 
age and  to  be  a  preventive  of  noxious  humors. 

Chrysoprase  and  prase  are  terms  applied  to  an  apple-green  to  bright 
green  chalcedony,  or  compact,  jasper-like  form  of  quartz.  Some  author- 
ities, however,  call  the  green  chalcedony  plasma,  and  restrict  the  term 
chrysoprase  to  the  green  compact  quartz.  The  terms  cannot  be  accur- 
ately distinguished.  Most  chrysoprase  now  in  use  comes  from  localities 

152 


in  the  province  of  Silesia,  in  Germany,  where  it  occurs  in  thin  layers 
and  veins  in  serpentine.  The  green  color  is  due  to  nickel  oxide, 
which  is  present  in  the  stone  to  the  amount  sometimes  of  one  per  cent. 
The  first  discovery  of  the  stone  is  said  to  have  been  made  by  a  Prussian 
officer  in  1740.  The  stone  was  especially  fancied  by  Frederick  the  Great, 
so  that  he  had  two  tables  made  of  it,  and  used  it  frequently  in  mosaics. 
The  color  fades  with  light  and  heat;  but  it  is  said  can  be  restored 
by  burying  the  stone  in  moist  earth  for  a  time.  Beautiful  chrysoprase 
comes  from  India,  and  there  are  a  few  localities  in  our  own  country 
where  it  is  found,  it  being  usually  associated  with  nickeliferous  deposits. 
The  name  chrysoprase  comes  from  two  Greek  words,  meaning  golden 
leek,  and  refers  to  the  color  of  the  stone.  By  the  ancients  it  was 
supposed  to  possess  the  virtues  of  the  emerald  though  in  less  degree. 
They  thought  that  it  lost  its  color  in  contact  with  poison,  and  was  an 
excellent  cordial  and  stimulant. 

Plasma,  as  already  stated,  is  a  name  applied  to  green  chalcedony, 
or  by  some  to  green  jasper.  The  name  comes  from  the  Greek  for  image, 
and  shows  that  the  stone  was  largely  used  for  seals  and  other  engraved 
work.  Most  of  that  known  at  the  present  time  comes  from  India 
and  China. 

Bloodstone  is  a  variety  of  plasma  containing  spots  of  red  jasper, 
looking  like  drops  of  blood.  Another  name  for  bloodstone,  by  which 
it  was  chiefly  known  by  the  ancients,  is  heliotrope.  This  name  is 
derived  from  two  Greek  words,  meaning  "  sun  turning,"  and  refers 
to  the  belief  that  the  stone  when  immersed  in  water  would  change 
the  image  of  the  sun  to  blood-red.  The  water  was  also  said  to  boil  and 
overflow  the  containing  basin.  As  late  as  the  middle  of  the  seventeenth 
century  bloodstone  was  used  as  a  cure  for  dyspepsia,  and  when  powdered 
and  mixed  with  honey  was  considered  a  remedy  for  tumors.  If  rubbed 
with  the  juice  of  the  heliotrope  it  was  supposed  to  render  its  wearer 
invisible.  It  was  often  used  for  stopping  the  flow  of  blood,  either  by 
touching  the  bleeding  spot  with  it,  or  by  wetting  the  stone  in  water 
and  holding  it  in  the  hand.  It  was  also  often  used  for  carvings 
representing  the  head  of  Christ,  one  fine  specimen  of  such  work  being 
preserved  in  the  Field  Columbian  Museum.  The  ancients  had  a  tradition 
that  the  stone  originated  at  the  crucifixion  of  Christ,  from  drops  of  blood 
drawn  by  the  spear  thrust  in  his  side,  falling  on  a  dark  green  jasper. 
The  stone  takes  a  beautiful  polish.  To  be  of  the  best  quality,  it  should 
have  a  rich,  dark  green  color,  and  the  red  spots  should  be  small  and 
uniformly  distributed^  The  supply  is  obtained  almost  wholly  from  India, 
especially  from  the/'Katniawar  Peninsula  west  of  Cambay,  whence  agate, 

153 


carnelian,  and  chalcedony  are  also  obtained.  Fine  examples  have  also 
come  from  Australia  and  a  few  from  Brazil. 

Agate  differs  from  other  forms  of  quartz  in  being  made  up  of 
minute  layers,  which  are  variegated  in  color.  The  colors  may  appear 
in  the  form  of  bands  or  clouds.  The  banded  agates  appear  to  be 
made  up  of  parallel  layers,  sometimes  straight,  but  more  often  wavy 
or  curved  in  outline.  These  layers  or  bands  differ  in  color  from 
one  another,  exhibiting  shades  of  white,  gray,  blue,  yellow,  red,  brown, 
or  black.  To  the  naked  eye  they  appear  to  vary  in  width  from  the 
finest  lines  to  a  width  of  a  quarter  of  an  inch  or  more.  In  reality,  all 
the  bands  visible  to  the  naked  eye  are  made  up  of  finer  ones,  to  be  seen 
only  with  the  microscope.  Thus  in  a  single  inch  of  thickness  of  agate 
Sir  David  Brewster,  using  the  microscope,  counted  seventeen  thousand 
and  fifty  layers.  Besides  differing  in  color,  the  layers  differ  in  trans- 
parency and  porosity,  and  these  properties  add  to  the  variegated  appear- 
ance of  the  agate. 

On  account  of  their  beauties  of  color  and  outline,  agates  have  been 
known  and  prized  from  the  earliest  times.  They  are  mentioned  by  many 
of  the  ancient  Greek  writers,  and  the  name  agate  is  a  corruption  of  the 
name  Achates,  a  river  in  Sicily,  whence  the  first  stones  of  this  kind  used 
by  the  Greeks  were  obtained.  This  and  neighboring  localities  continued 
to  be  the  source  of  supply  until  the  fifteenth  century,  when  agates  were 
found  to  occur  in  large  quantities  near  Oberstein  and  Idar,  on  the  banks 
of  the  River  Nahe,  in  the  duchy  of  Oldenburg. 

The  industry  of  cutting  and  polishing  agates  on  a  large  scale  was 
soon  established  there,  and  these  places  are  to  this  day  the  center  of  the 
agate  industry.  The  agates  used  most  extensively  at  the  present  time 
are  not,  however,  those  found  about  Oberstein,  but  come  from  a  region 
about  one  hundred  miles  in  length,  extending  from  the  Province  of  Rio 
Grande  do  Sul  in  Southern  Brazil  into  Northern  Uruguay.  The  agates 
in  this  region,  first  discovered  in  1827,  so  surpass  in  size  and  beauty 
those  from  any  other  known  locality,  that  they  form  at  the  present  time 
almost  the  only  source  of  supply.  They  are  shipped  in  large  quantities 
as  ballast  to  Oberstein  and  Idar,  and  here  the  work  of  cutting,  polishing, 
and  coloring  them  is  performed.  The  discovery  that  the  attractiveness 
of  agates  could  be  enhanced  by  artificial  coloring  was  made  about  the 
beginning  of  the  nineteenth  century.  The  natural  colors  are  rarely  of  a 
high  order,  being  often  only  variations  of  white  and  gray,  or  dull  yellows 
and  reds.  Through  the  difference  of  porosity  of  the  different  layers, 
however,  and  the  consequent  different  absorption  of  coloring  ingre- 
dients, colors  can  be  artificially  introduced  which  produce  lasting  and 

154 


422 


Banded  Agate  (Brazil). 


AGATE. 

Banded  Agate  (Lake  Superior). 
Moss  Agate. 


COPYRIGHT    1901,  BY  A.   W.   MUMFORD,   CHICASO. 


Clouded  Agate. 


pleasing  effects.  Most  agate  used  for  ornamental  purposes  at  the  present 
time  is,  therefore,  artificially  colored.  The  method  of  coloring  is  to  boil 
the  stone  in  honey  for  a  number  of  days,  or  even  weeks,  according 
to  the  porosity  of  the  agate  and  the  color  desired,  then  to  immerse  it 
in  hot  sulphuric  acid.  The  acid  chars  to  a  brown  or  black  the  carbon 
of  the  honey  which  has  been  absorbed  by  the  stone.  Various  coloring 
ingredients,  such  as  oxides  of  iron,  salts  of  nickel,  Prussian  blue,  etc., 
may  be  added  to  the  liquids  employed  at  some  stage  of  the  process, 
and  thus  different  colors  be  obtained. 

Agates  of  considerable  beauty,  though  not  of  great  size,  are  found  in 
many  places  in  the  United  States.  Those  of  Agate  Bay,  Lake  Superior, 
have  rich  colors,  and  make  attractive  charms  and-  other  ornaments. 
Agates  are  found  in  the  beds  of  many  streams  in  Colorado,  Montana, 
and  other  regions  of  the  Rocky  Mountains.  They  occur  all  along  the 
Mississippi  River,  especially  in  Minnesota,  also  along  the  Fox  River,  Illi- 
nois, in  the  trap  rocks  along  the  Connecticut  River,  and  on  the  coast  of 
California.  While  many  of  these  agates  are  of  great  beauty,  their  use 
and  sale  is  not  likely  to  be  anything  more  than  local,  since  the  Brazilian 
agates  can  be  supplied  so  cheaply  from  Germany. 

The  layered  structure  of  agates  is  due  to  successive  depositions 
of  silica  by  water  flowing  through  cavities  in  rocks.  Rising  and  falling 
alternately  through  the  rocks  the  water  leaves  a  mark  of  each  advance 
or  retreat  in  the  form  of  an  additional  layer  deposited  upon  the  interior 
walls  of  the  cavity.  Agates,  therefore,  grow  from  the  outside  inward. 
The  process  may  go  on  until  the  cavity  is  entirely  filled  or  may  cease 
at  any  time.  If  the  cavity  is  small  and  nearly  circular,  and  becomes 
entirely  filled,  the  kind  of  agate  known  as  "eye-agate"  is  produced. 
If  water  remains  in  the  cavity  for  some  time  crystals,  such  as  are  some- 
times seen,  will  be  formed.  The  nodule  of  silica  or  agate  formed  by 
the  percolating  waters  is  harder  and  more  resistant  than  the  surround- 
ing rock.  Hence  it  remains  after  the  surrounding  rock  has  been  worn 
away.  We  can  thus  understand  why  agates  should  be  found,  as  they 
usually  are,  on  sea  or  lake  beaches,  or  in  the  beds  of  streams. 

The  different  colors  seen  in  the  natural  agates  are  produced  by  traces 
of  organic  matter  or  of  oxides  of  iron,  manganese  or  titanium  contained 
in  the  waters  which  formed  them. 

Agates  are  not  used  as  extensively  as  they  once  were  for  ornamental 
purposes.  In  the  years  of  1848-50  agate  jewelry  was  very  fashionable, 
and  was  extensively  worn.  At  the  present  time,  however,  the  principal 
use  of  agate  in  jewelry  is  for  breastpins  and  watch-charms.  For  orna- 
mental purposes  it  is  used  in  pen-holders,  knife-handles,  and  vases.  Its 

155 


use  for  large  marbles  was  once  quite  common,  but  glass  marbles  of  the 
same  size,  and  still  called  "agates,"  are  now  generally  substituted.  In 
fine  mechanical  work,  such  as  bearings  for  delicate  instruments,  and  in 
tools  for  polishing  and  grinding,  agate  is  still  extensively  used. 

Various  curative  properties  were  formerly  attributed  to  the  agate, 
belief  in  some  of  which  still  survives,  especially  among  Mohammedan 
peoples.  It  was  regarded  as  a  cure  for  insanity,  and  as  a  preventive  of 
skin  diseases.  It  symbolized  health  and  wealth,  and  was  supposed  to 
render  its  wearer  gracious  and  eloquent. 

Onyx  and  sardonyx  are  varieties  of  agate  in  which  the  layers  are  in 
even  planes  of  uniform  thickness.  This  structure  enables  the  stone  to 
be  used  for  engraving  cameos.  As  is  well  known,  these  are  so  made  that 
the  base  is  of  one  color  and  the  figure  of  another.  This  art  of  making 
cameos  reached  a  high  degree  of  perfection  among  the  Romans,  and 
many  superb  examples  of  it  have  come  down  to  us.  The  word  onyx 
means  a  nail  (finger-nail),  and  refers  to  some  fancied  resemblance,  per- 
haps in  luster,  to  the  human  nail.  Sardonyx  is  a  particular  variety 
of  onyx  in  which  one  of  the  layers  has  the  brown  color  of  sard.  Other 
kinds  of  onyx  are  those  known  as  chalcedonyx  and  carnelionyx,  in  refer- 
ence to  the  color  of  the  intervening  layers.  So-called  Mexican  onyx  is 
composed  of  quite  a  different  mineral  from  the  onyx  here  considered,  it 
being  made  up  of  calcite  rather  than  quartz.  Hence  Mexican  onyx  can  be 
scratched  easily  with  a  knife,  while  quartz  onyx  cannot.  Mexican  onyx 
has,  however,  the  banded  structure  of  quartz  onyx,  and  it  is  in  allusion 
to  this  undoubtedly  that  the  name  has  been  applied.  A  sardonyx  upon 
which  Queen  Elizabeth's  portrait  was  cut  constituted  the  stone  of  the 
famous  ring  which  she  gave  the  Earl  of  Essex  as  a  pledge  of  her  friend- 
ship. It  will  be  remembered  that  when  the  earl  was  sentenced  to  death 
he  sent  this  ring  to  his  cousin,  Lady  Scroop,  to  deliver  to  Elizabeth. 
The  messenger  by  mistake  gave  it  to  Lady  Scroop's  sister,  the  Countess 
Nottingham,  who  being  an  enemy  of  the  earl's  did  not  deliver  it  to  the 
queen,  and  the  earl  was  executed.  On  her  deathbed  the  countess  is  said 
to  have  confessed  her  crime  to  the  queen,  who  was  so  infuriated  that  she 
shook  her,  saying  "God  may  forgive  you,  but  I  cannot." 

In  the  Middle  Ages  sardonyx  was  used  as  an  eyestone,  and  is  employed 
in  Persia  to  this  day  for  the  cure  of  epilepsy.  It  was  supposed  by  the 
ancients  to  be  an  entirely  different  stone  from  the  onyx.  To  it  was  ascribed 
the  property  of  conferring  eloquence  upon  its  wearer,  and  it  especially  sym- 
bolized conjugal  bliss-.  It  is  mentioned  in  Revelations  as  one  of  the  stones 
forming  the  foundations  of  the  Holy  City.  Onyx  and  sardonyx  which 
come  from  the  Orient  are  esteemed  of  much  higher  value  in  trade  at  the 

156 


41)9 


QUARTZ  (obscurely  crystalline). 


Bloodstone,  polished  (India). 
Tiger  Eye,  polished  (South  Africa). 


Chrysoprase  (Silesia). 
Agate  and  Carrielian,  polished  (Lake  Superior). 


Jasper  (Germany). 

Kibbon  Jasper,  polished  (Siberia). 


present  time  than  those  prepared  in  Germany.  There  seems  to  be  no 
good  reason  for  this,  however,  as  the  latter  can  be  so  skillfully  made 
that  it  is  impossible  to  distinguish  them  from  the  Oriental  stones. 

Jasper  includes  in  general  nearly  all  varieties  of  impure,  opaque, 
colored,  crypto-crystalline  quartz.  In  color  it  may  be  red,  yellow,  green, 
brown,  bluish,  and  black.  To  many  of  the  pebbles  found  on  almost  any 
sea  or  lake  shore,  or  in  the  beds  of  streams,  the  name  jasper  may  prop- 
erly be  applied.  If  it  occurs  banded,  that  is,  in  stripes  of  different  colors, 
it  is  known  as  ribbon  jasper.  The  different  colors  of  jasper  are  due 
to  different  impurities  which  it  contains.  These  may  be  clay,  iron 
oxides,  or  organic  matter,  and  at  times  reach  a  quantity  as  high  as 
twenty  per  cent.  The  color  often  varies  irregularly  in  a  single  stone, 
giving  different  effects,  and  sometimes  imitating  paintings.  Jasper 
which  can  be  used  in  the  arts  is  very  widely  distributed.  Good  red 
jasper  is  obtained  in  Breisgau,  and  near  Marburg  in  Germany.  Much 
brown  jasper  comes  from  Egypt.  What  is  known  as  "  Sioux  Falls 
jasper,"  from  Sioux  Falls,  South  Dakota,  is  chiefly  of  a  brown  color. 
This  stone  was  highly  prized  by  the  Indians  for  its  color,  and  is  the 
"jasper"  referred  to  by  Longfellow  in  Hiawatha: 

"At  the  doorway  of  his  wigwam 
Sat  the  ancient  Arrow-maker 
In  the  land  of  the  Dacotahs, 
Making  arrow-heads  of  jasper, 
Arrow-heads  of  chalcedony." 

The  yellow  jasper  used  for  mosaics  comes  chiefly  from  Sicily,  but 
as  good  could  be  obtained  in  many  places  in  our  own  country.  The 
green  jasper  of  the  present  time  is  obtained  chiefly  in  the  Urals,  and 
is  to  a  considerable  extent  worked  there  into  ornamental  pieces.  The 
Chinese^  prize  green  jasper  highly,  the  seal  of  the  emperor  being  made 
from  it.  Some  jasper  of  a  bluish  shade  is  found  in  nature;  but  that 
of  a  deep  blue  tinge  is  always  artificially  colored  by  Prussian  blue. 
It  is  then  sometimes  known  as  "  false  lapis  ";  that  is,  false  lapis  lazuli. 
Kibbon  jasper  is  found  in  Saxony,  but  chiefly  comes  from  the  Urals. 
The  qualities  which  make  jasper  of  use  in  the  arts  are  its  color, 
opacity,  and  capacity  for  taking  a  polish.  At  the  present  time  it 
is  not  much  used  except  for  mosaic  work,  and  for  small  boxes,  vases, 
and  dishes.  The  ancients,  however,  prized  it  highly  and  used  it  exten- 
sively. It  is  one  of  the  stones  prescribed  in  the  Book  of  Exodus  to  be 
worn  in  the  ephod  of  the  high  priest,  and  also  forms  one  of  the  gates 
of  the  Holy  City,  as  described  by  St.  John  in  Revelations.  It  is  prob- 
able that  the  jasper  referred  to  in  these  instances  was  of  a  dark  green 

157 


color,  as  this  was  the  tint  most  prized  in  early  times.  Green  jasper 
was  also  called  emerald  in  some  instances.  The  banded  varieties  were 
much  used  for  cameos,  specimens  of  which  are  still  extant.  By  taking 
advantage  of  the  colors  of  the  different  layers,  colored  objects  were 
made,  such  as  one  which  shows  the  head  of  a  warrior  in  red,  his  helmet 
green,  and  breastplate  yellow. 

Jasper  worn  as  an  amulet  was  regarded  a  preventive  of  sorrow,  and 
mottled  jasper  suitably  engraved  was  believed  to  protect  its  wearer  from 
death  by  drowning.  It  was  a  charm  against  scorpions  and  spiders,  and 
strengthened  the  chest,  lungs  and  stomach,  according  to  beliefs  held  in 
the  Middle  Ages. 

Basanite,  also  known  as  Lydian  stone,  or  touchstone,  is  chiefly  used 
for  trying  the  purity  of  metals.  Its  value  for  this  purpose  depends  on  its 
hardness,  peculiar  grain,  and  black  color.  Different  alloys  of  gold  give 
different  colors  on  the  stone,  and  thus  enable  one  to  determine  the  fine- 
ness of  the  gold.  Also,  if  an  object  is  plated,  by  giving  it  a  few  strokes 
on  the  stone,  the  different  color  of  the  gold  and  base  will  be  revealed. 
Basanite  is  a  black  variety  of  crypto-crystalline  quartz,  differing  from 
jasper  in  being  tougher  and  of  finer  grain,  and  from  hornstone  in  not 
being  splintery. 

Flint  is  likewise  an  opaque  quartz  of  dull  color.  It  differs  from 
jasper  in  breaking  with  a  deeply  conchoidal  fracture  and  a  sharp 
cutting  edge.  It  is  also  often  slightly  transparent,  and  has  a  some- 
what glassy  luster.  These  properties  have  led  to  its  extensive  use 
by  the  Indians  and  by  nearly  all  primitive  peoples  for  the  manufac- 
ture of  weapons  and  implements.  Hornstone  is  more  brittle  than 
flint,  and  has  a  splintery  rather  than  a  conchoidal  fracture.  A  num- 
ber of  other  subvarieties  of  crypto-crystalline  quartz  occur,  but  they 
are  not  important  as  gems. 


158 


477 


Precious  Opal  in  matrix  (Queensland). 
Precious  Opal  (New  South  Wales). 


OPAL. 

Wood  Opal  (Idaho). 

Precious  Opal  (New  South  Wales). 

Prase  Opal  (Germany). 


Precious  Opal  (New  South  Wales). 
Fire  Opal  in  matrix  (Mexico). 


OPAL 

"The  opal,  when  pure  and  uncut  in  its  native  rock,"  says  Ruskin 
in  his  lecture  on  Color,  "  presents  the  most  lovely  colors  that  can  be 
seen  in  the  world,  except  those  of  clouds." 

While  not  all  may  share  the  great  art  critic's  preference  for  uncut 
stones,  there  are  few  probably  who  do  not  join  heartily  in  admiration 
of  the  brilliant  gem  from  whose  depths  come  welling  up  tints  of  so 
varied  hue  that  we  appropriately  speak  of  them  as  colors  at  play. 
Regarding  these  colors  Ruskin  says  further :  "  We  have  thus  in  nature, 
chiefly  obtained  by  crystalline  conditions,  a  series  of  groups  of  entirely 
delicious  hues ;  and  it  is  one  of  the  best  signs  that  the  bodily  system 
is  in  a  healthy  state  when  we  can  see  these  clearly  in  their  most 
delicate  tints,  and  enjoy  them  fully  and  simply  with  the  kind  of 
enjoyment  that  children  have  in  eating  sweet  things.  I  shall  place 
a  piece  of  rock  opal  on  the  table  in  your  working -room;  and  if 
on  fine  days  you  will  sometimes  dip  it  in  water,  take  it  into  sun- 
shine, and  examine  it  with  a  lens  of  moderate  power,  you  may  always 
test  your  progress  in  sensibility  to  color  by  the  degree  of  pleasure  it 
gives  you." 

The  opal  is  indeed  one  of  the  most  fascinating  of  gems;  yet  often 
elusive,  and  at  times  disappointing.  Of  its  freaks  and  foibles  strange 
stories  are  told.  Gems  of  brilliant  quality  sometimes  lose  their  hues 
never  to  regain  them,  and  others  previously  dull  and  lusterless  become 
radiant.  Professor  Egleston,  of  New  York  City,  once  related  that 
a  bottle  of  cut  opals  given  him  by  a  prominent  jewelry  firm  because 
they  had  lost  their  color,  after  remaining  in  his  cabinet  for  a  time 
regained  their  brilliancy  and  retained  it.  But  to  have  opals  regain 
their  color  is,  unfortunately,  far  less  usual  than  for  them  to  lose  it. 
The  gem  often  exhibits  brilliant  colors  when  wet  either  with  water 
or  oil  that  disappear  when  it  is  dry.  Taking  advantage  of  this 
peculiarity  dishonest  dealers  often  keep  opals  immersed  until  just 
before  offering  them  for  sale.  Purchasers  of  opals  of  this  sort 
have  good  reason  to  believe  the  superstition  commonly  attached  to 
the  opal  that  it  is  an  unlucky  gem.  Some  authorities,  however,  trace 
the  origin  of  the  superstition  to  Sir  Walter  Scott's  novel  "Anne 

159 


of  Geierstein,"  in  which  the  baleful  influence  of  the  opal  plays  a  promi- 
nent part;  and  it  is  stated  that  within  a  year  of  the  publication  of  the 
book  the  price  of  opals  declined  fifty  per  cent  in  the  European  market. 
Even  if  the  superstition  did  not  originate  in  either  of  these  ways,  it  was 
probably  from  a  source  quite  as  trivial,  and  it  should  prevent  no  one 
from  enjoying  the  pleasure  to  be  derived  from  the  beauties  of  this  gem. 

Chemically,  opal  is  oxide  of  silicon,  with  varying  amounts  of  water, 
the  variation  being  from  3  to  9  per  cent.  It  is,  therefore,  closely 
allied  to  quartz,  but  differs  physically  in  being  softer  and  not  as  heavy. 
Further,  it  never  crystallizes,  and  is  soluble  in  caustic  potash,  which 
quartz  is  not.  It  is  infusible,  but  cracks  and  becomes  opaque  before 
the  blowpipe.  In  sulphuric  acid  it  turns  black,  on  account  probably 
of  the  organic  matter  it  contains. 

Its  hardness  is  sometimes  as  low  as  5.5,  though  generally  6.  Its 
specific  gravity  is  from  1.9  to  2.3.  On  account  of  its  relative  softness 
a  cut  opal  often  does  not  retain  its  polish  well,  and  requires  frequent 
smoothing.  Opals,  when  first  taken  from  the  ground,  are  often  softer 
even  than  the  above,  and  for  this  reason  it  is  usual  and  desirable 
to  allow  them  to  harden,  or  "  season,"  as  it  is  called,  for  some  time 
after  quarrying  before  they  are  polished. 

Opal,  as  a  mineral,  is  quite  common,  so  that  no  one  need  suppose 
because  he  has  specimens  labeled  "  opal "  in  his  collection  that  he  has 
as  many  precious  stones.  It  occurs  in  many  varieties;  and,  especially 
if  it  contains  foreign  matter,  in  many  colors.  Nearly  all  silica  deposited 
by  hot  waters  is  in  the  form  of  opal,  so  that  the  geysers  of  Yellowstone 
Park  build  up  cones  of  opal  and  fall  into  opal  basins.  This  particular 
form  of  opal  is  known  as  geyserite,  and  it  is  often  differently  colored 
by  different  ingredients. 

Wood  is  often  preserved  by  silica  in  the  form  of  opal,  the  siliceous 
waters  taking  away  the  wood  and  replacing  it  by  opal,  grain  by  grain, 
with  such  delicacy  and  accuracy  that  the  structure  of  the  wood  is  per- 
fectly maintained.  The  minute  shells  which  diatoms  make  consist 
of  opal,  and  when  these  dead  shells  accumulate  to  form  deposits 
of  some  extent  we  call  the  powdery  substance  tripoli,  and  use  it  for 
polishing  silverware  and  other  metals.  Other  varieties  of  opal  include 
hyalite,  a  variety  looking  like  transfixed  water,  so  clear  and  colorless 
is  it;  hydrophane,  a  translucent  variety  which  sticks  to  the  tongue  and 
becomes  nearly  or  quite  transparent  when  soaked  in  water ;  cacholong, 
a  porcelain-like  variety ;  and  menilite,  a  concretionary  variety. 

Common  opal  varies  from  transparent  to  opaque,  being  most  often 
translucent,  and  sometimes  exhibiting  the  peculiar  milkiness  of  color 

160 


which  we  call  opalescence.  It  has  sometimes  a  glassy,  but  often  a  waxy, 
luster,  the  latter  when  pronounced  giving  rise  to  the  varieties  known 
as  wax  opal  and  resin  opal.  When  opal  has  the  banded  structure 
of  agate  it  is  known  as  opal-agate ;  when  it  has  the  color  of  jasper, 
as  jasper-opal;  and  when  that  of  chrysoprase,  as  prase-opal.  But  none 
of  these  varieties  is  used  in  any  quantity  as  gems.  This  distinction 
is  reserved  almost  wholly  for  the  variety  known  as  noble  or  precious 
opal.  This  is  opal  which  exhibits  a  play  of  colors.  No  essential  chem- 
ical or  physical  distinction  between  noble  opal  and  other  varieties 
is  known.  In  a  large  vein  of  opal  portions  will  exhibit  the  play 
of  colors  and  the  remainder  will  not;  but  why  the  difference  has  not 
yet  been  determined.  The  uncolored  opal  is  known  by  the  Australian 
miners  as  "potch,"  while  that  which  is  precious  is  known  as  "colors." 
The  origin  of  the  varied  coloring,  i.  e.,  the  iridescence,  is  not  positively 
known.  Some  regard  it  as  due  to  interspersed  layers  containing  differ- 
ent percentages  of  water,  which  break  up  the  rays  of  light  somewhat 
as  a  prism  does,  while  others  think  that  minute  cracks  and  fissures 
through  the  stone  furnish  surfaces  from  which  the  rays  are  reflected 
in  different  colors  back  to  the  eye.  Some  opals  which  are  dull  and 
lusterless  when  dry,  exhibit  considerable  play  of  color  when  immersed 
in  water,  and  this  fact  seems  to  favor  the  first  theory  of  the  cause 
of  the  iridescence,  but  the  subject  is  not  understood.  The  character 
of  the  play  of  colors  differs  in  different  opals,  and  this  gives  rise 
to  different  varieties.  The  true  noble  opal  has  the  color  quite  uni. 
formly  distributed.  When  the  color  appears  in  flashes  chiefly  of  red 
and  yellow,  the  stone  is  known  as  fire  opal;  of  blue,  as  girasol;  apd 
chiefly  of  yellow,  as  golden  opal.  When  the  patches  of  color  are  small, 
angular,  and  uniformly  distributed  the  stone  is  called  harlequin  opal,  and 
if  these  are  long  and  somewhat  parallel,  flame  opal.  These  colors 
are  not,  of  course,  inherent  in  the  stone,  its  color  varying  from  color- 
less to  opaque  -  white.  The  black  opals  sometimes  seen  are  usually 
of  artificial  origin,  being  made  by  soaking  ordinary  opals  in  oil  and 
then  burning  the  oil.  The  brilliancy  of  the  stone  is  thus  increased ;  but 
it  is  made  fragile  and  liable  to  lose  color.  Any  opal,  however,  may 
lose  its  play  of  colors  on  being  heated  too  highly.  It  is  the  variety 
and  brilliancy  of  the  changing  colors  which  give  to  opal  nearly  all  its 
desirability  as  a  precious  stone,  for  the  qualities  of  hardness,  trans- 
parency, and  rich  body  color,  which  give  to  most  other  gems  their 
value,  are  lacking  in  it.  But,  together  with  the  beauty  of  its  changing 
colors,  opal  possesses  an  advantage  over  all  other  gems  in  that  it  can- 
not be  successfully  imitated.  It  is  said  that  the  Romans  were  able  to 

161 


make  artificial  opals  closely  resembling  the  real ;  but  the  art  has  never 
been  fully  recovered,  and  we  may  hope  it  never  will  be.  Hence,  however 
much  danger  there  may  be  in  buying  an  opal  that  has  not  been  properly 
"  seasoned,"  or  one  that  may  lose  its  play  of  color,  the  purchaser  may 
at  least  be  sure  he  has  an  opal  and  not  an  imitation.  The  stones  are 
usually  cut  in  the  cabochon  form,  this  cutting  being  found  to  bring  out 
their  brilliancy  better  than  any  facetted  form.  The  brilliancy  of  the 
stone  may  be  increased  in  setting  by  giving  it  a  backing  of  mother-of- 
pearl,  or  black  silk.  When  a  number  of  opals  are  placed  together  they 
seem  to  borrow  brilliancy  from  one  another,  a  fact  which  is  taken  ad- 
vantage of  in  settings  by  placing  a  number  together,  and  also  by  opal 
dealers  to  dispose  of  inferior  stones  by  grouping  them  with  good  ones. 
For  this  reason  when  opals  are  purchased  they  should  be  examined  sep- 
arately. The  value  of  opals  depends  almost  wholly  on  the  brilliancy  of 
their  coloring  and  their  size.  Stones  without  the  play  of  colors  are  prac- 
tically worthless,  while  stones  of  ten  to  twenty  carats'  weight,  with  bril- 
liant coloring,  may  bring  several  hundred  dollars.  The  most  highly 
valued  opals  have  long  come  from  the  mines  oj:  Czernowitza,  in  northern 
Hungary.  These  opals  are  often  known  as  Oriental  opals,  from  the  fact 
that  in  early  days  they  were  first  purchased  by  Greek  and  Turkish  mer- 
chants, and  by  them  sent  to  Holland.  There  are,  however,  no  known 
localities  in  the  Orient  where  precious  opals  are  found.  The  rock  in 
which  the  Hungarian  opals  occur  is  eruptive,  and  of  the  kind  known 
as  andesite.  It  is  considerably  decomposed,  and  the  opal  occurs  in  clefts 
and  veins.  There  is  little  doubt  that  it  was  from  these  mines  that  the 
Romans  obtained  the  opals  known  to  them,  and  the  output  has  been  quite 
constant  since.  It  is  said  that  the  Hungarian  opals  are  less  likely  to 
deteriorate  than  any  others.  Still  the  danger  of  deterioration  is  not  great 
in  any  opal.  The  other  important  countries  from  which  precious  opals 
are  obtained,  are  Mexico,  Honduras,  and  Australia.  The  Mexican  opals 
are  mostly  of  the  fire  opal  variety.  They  are  mined  in  a  number  of  the 
States  of  the  Republic — Queretaro,  Hidalgo,  Guerrero,  Michoacan,  Jalisco, 
and  San  Luis  Potosi.  The  oldest  mines  are  in  the  State  of  Hidalgo, 
near  Zimapan,  where  the  opal  occurs  in  a  red  trachyte.  Most  of  the 
Mexican  opals  on  the  market  at  the  present  time,  however,  come  from 
the  State  of  Queretaro,  where  mining  for  them  is  conducted  on  an 
extensive  scale.  The  opal  here  occurs  in  long  veins,  in  a  porphyritic 
trachyte,  and  is  mined  at  various  points.  The  stones  are  cut  and 
polished  by  workmen  in  the  city  of  Queretaro,  who  use  ordinary  grind- 
stones and  chamois  skins  for  the  work,  and  are  said  to  receive  an  aver- 
age wage  of  twenty-three  cents  a  day.  The  ^Honduras  opals  reach 

162 


O 
00 


foreign  markets  but  rarely  and  usually  uncut.  The  mines  are  chiefly  in 
the  western  part  of  Honduras,  in  the  Department  of  Gracias,  but  good 
opals  also  occur  in  the  mountains  on  the  boundary  between  Honduras 
and  San  Salvador.  They  are  little  worked,  but  there  is  no  doubt  that 
extensive  deposits  exist  which  might  afford  a  good  supply  of  gems  if 
they  were  properly  exploited.  The  Australian  opals  come  from  several 
localities,  the  most  prominent  at  the  present  time  being  White  Cliffs, 
New  South  Wales.  The  matrix  is  a  Cretaceous  sandstone,  which  has 


>  y/ ,        s  **?;f* C  *  - 


Opal  mines,  White  Cliffs,  New  South  Wales 

been  permeated  by  hot,  volcanic  waters.  Shells,  bones,  and  other  fossils 
are  found  here  entirely  altered  to  precious  opal,  making  objects  of  great 
beauty.  In  1899  opals  to  the  value  of  $650,000  were  sold  from  this 
single  region.  There  is  no  doubt  that  the  present  popularity  of  the 
opal  is  due  to  some  extent  to  the  supply  of  beautiful  stones  which  has 
come  from  these  mines,  at  prices  one-third  to  one-tenth  those  of  the 
Hungarian  stones.  Other  localities  in  Australia  whence  precious  opals 
are  obtained  are  places  on  the  Barcoo  River  and  Bulla  Creek,  Queens- 
land, and  occasional  finds  in  West  Australia. 

No  localities  in  the  United  States  yielding  precious  opals  in  any 

163 


quantity  have  yet  been  discovered.  Some  good  stones  have  been  cut 
from  an  occurrence  in  Idaho,  and  some  other  minor  finds  have  been 
made,  but  they  possess  little  commercial  importance  at  present. 

Opal  does  not  seem  to  have  been  extensively  known  or  used  by 
the  ancients,  although  the  Romans  prized  it  highly,  and  ascribed  to  it 
the  power  of  warning  against  disaster.  They  named  it  the  Paideros,  or 
Cupid,  and  regarded  it  the  perfection  of  beauty.  Pliny  describes  it  as 
combining  the  fire  of  the  ruby,  the  purple  of  the  amethyst,  and  the  sea- 
green  of  the  emerald,  all  shining  together  in  an  indescribable  union. 
The  Roman  senator  Nonius  owned  one  set  in  a  ring,  which  was  said  to 
be  valued  at  nearly  a  million  dollars.  History  records  that  for  refusing 
to  sell  the  stone  to  Mark  Antony  he  was  sent  into  exile.  This  stone  was, 
however,  no  larger  than  a  hazelnut,  and  would  probably  be  worth  hardly 
a  hundred  dollars  at  the  present  day.  The  next  most  famous  opal  in 
history  is  one  that  was  owned  by  the  Empress  Josephine,  and  called 
"The  Burning  of  Troy,"  on  account  of  the  brilliancy  of  the  flames 
which  shot  forth  from  its  depths.  The  present  whereabouts  of  neither 
of  these  gems  is  known.  A  large  Mexican  opal,  now  in  the  Field 
Columbian  Museum,  is  carved  in  the  image  of  the  Mexican  sun-god, 
and  has  a  setting  of  gold  representing  the  diverging  rays  of  the  sun. 
This  gem  is  very  ancient,  and  is  believed  to  have  been  kept  in  a  Persian 
temple.  To  the  opal  was  assigned,  in  the  sixteenth  century,  the  power 
of  making  its  wearer  a  general  favorite,  enhancing  the  keenness  of  his 
sight,  and  shielding  him  from  suicide.  The  name  opal  is  from  the  Greek 
word  for  eye,  and  shows  the  esteem  in  which  the  gem  was  held  for  treat- 
ing diseases  of  that  organ.  It  was  also  supposed  to  have  the  virtues  of 
all  the  stones  whose  colors  it  showed.  It  was  believed  to  stimulate  the 
heart,  cheer  the  despondent,  and  preserve  from  contagion.  Like  the  tur- 
quois,  its  color  was  supposed  to  change  if  its  wearer  grew  ill,  and  regain 
it  when  he  recovered.  It  symbolized  hope  also.  The  belief  in  its  bring- 
ing ill-luck  is  of  more  modern  origin,  and  confined  to  Occidental  peoples. 

Possession  of  a  black  opal  is  regarded  in  India,  at  the  present  time,  as 
productive  of  good  fortune. 


164 


JADE 

Jade  is  a  term  applied  in  general  to  a  tough,  fibrous  mineral  of  a 
greenish  color  having  the  composition  of  a  pyroxene  or  amphibole. 
Until  recently  the  mineral  was  supposed  to  form  a  single  species,  but 
it  is  now  known  that  at  least  two  species  are  grouped  under  this  title. 
One  of  these  is  a  form  of  pyroxene,  and  is  known  as  jadeite,  the  other 
is  a  form  of  amphibole,  and  is  named  nephrite.  Further,  the  term  is 
often  used  to  include  any  tough  green  stone  having  a  hardness  between 
6  and  7  and  taking  a  good  polish,  since  such  rocks  or  minerals  are  often 
carved  by  people  who  use  true  jade.  Jadeite  is  a  mineral  of  definite 
composition,  it  being  a  silicate  of  soda  and  alumina.  The  percentage 
composition  of  pure  jadeite  is.  silica  59.4  per  cent,  alumina  25.2  per 
cent,  and  soda  15.4  per  cent.  Its  hardness  is  a  little  below  that  of 
quartz,  or  between  6.5  and  7,  but  its  extreme  toughness  makes  it  often 
seem  harder  than  this.  It  is  a  rather  heavy  mineral,  its  specific  gravity 
being  3.35.  In  color  it  varies  from  nearly  white  to  nearly  emerald-green. 
The  white  varieties  sometimes  contain  spots  of  bright  green,  supposed  to 
be  due  to  chromium.  The  mineral  does  not  crystallize,  but  is  known  from 
its  optical  properties  to  be  either  monoclinic  or  triclinic.  It  does  not 
occur  transparent,  but  has  a  peculiar  translucency  or  subtranslucency  not 
unlike  that  of  horn  or  fine  porcelain.  It  has  a  fibrous  to  granular 
structure  readily  seen  under  the  microscope,  and  a  splintery  fracture.  It 
is  very  tough.  Jadeite  fuses  readily  before  the  blowpipe  to  a  trans- 
parent, blebby  glass,  and  colors  the  flame  yellow,  thus  differing  from 
nephrite,  which  is  almost  infusible.  The  term  chloromelanite  is  applied 
to  a  dark  green  to  black  jadeite  containing  considerable  iron. 

Objects  of  jadeite  carved  in  prehistoric  times  are  found  abundantly 
in  Europe,  Asia,  America,  and  Africa,  but  only  a  few  of  the  original 
localities  whence  it  was  obtained  are  now  known.  ^The  most  important 
locality  known  at  the  present  time  is  in  Upper  Burmah  in  the  vicinity 
of  Mogoung.  The  jadeite  occurs  in  boulders  embedded  in  a  reddish 
yellow  clay  in  the  valleys  of  tributaries  of  the  Dschindwin  River.  The 
boulders  are  mined  by  digging  shallow  pits  after  the  fashion  of  the  Bur- 
mese miners,  as  many  as  a  thousand  men  often  being  employed  in  this 
work.  The  miners  break  the  boulders  by  heating,  and  when  pieces  of 

165 


quality  suitable  for  cutting  are  found,  they  are  either  laid  aside  to  sell  to 
caravans  which  come  to  the  mines  for  this  purpose  from  China,  or  are 
turned  over  to  native  artisans,  who  reduce  them  to  desired  shapes  by 
sawing  them  with  steel  wire  strung  on  a  bamboo  bow.  The  jadeite 
from  this  locality  is  commercially  distributed  all  over  China,  where  it  is 
held  in  high  esteem,  and  commands  a  high  price.  Bauer  states  that  he 
saw  a  piece  containing  less  than  three  cubic  feet  which  was  valued  at 
$50,000.  The  jadeite  of  milk-white  color  is  that  most  highly  esteemed, 
although  that  with  bright  green  spots  is  also  considered  of  superior  value.  / 

Nephrite  is  a  variety  of  amphibole  much  resembling  jadeite  in  color, 
hardness,  and  texture.  It  is,  however,  of  somewhat  lower  specific  gravity 
than  jadeite,  ranging  as  it  does  from  2.96  to  3.1,  and  it  fuses  with  much 
greater  difficulty.  Under  the  microscope  a  section  shows  a  finely  fibrous 
character  differing  from  that  of  the  broad  fibers  or  granules  of  jadeite, 
and  the  optical  characters  throughout  are  those  of  an  amphibole  rather 
than  of  a  pyroxene.  In  composition  nephrite  is  a  silicate  of  calcium  and 
magnesium,  having  the  theoretical  percentages,  silica  57.7,  magnesia  28.9, 
and  lime  13.4.  A  little  alumina,  iron,  and  soda  are  often  found  combined 
with  the  above.  Nephrite  has  the  glistening  luster  and  semi-translu- 
cency  of  jadeite,  and  like  that  mineral  breaks  with  a  splintery  fracture. 
It  is  not  attacked  by  acids.  It  does  not  occur  in  distinct  crystals. 

<^The  most  important  locality  for  nephrite  at  the  present  time  is 
Turkestan,  where  it  occurs  in  the  Karakash  Valley  in  the  Kuen  Lun 
Mountains,  and  at  other  points  in  the  same  range.  In  these  localities  it 
forms  layers  in  gneiss  and  amphibole  schists.  It  is  very  pure  and  trans- 
lucent. Some  of  the  mines  have  been  worked  for  over  two  thousand  years. 
//•Nephrite  of  excellent  quality  also  occurs  in  eastern  Siberia  in  the 
beds  of  the  Onot  and  Chara  Jalga  rivers.  It  occurs  here  as  boulders, 
one  of  which  is  described  as  being  twelve  feet  in  length  and  three  feet 
in  width;  it  is  also  found  in  place.  A  canopy  thirteen  feet  in  height 
has  been  made  for  the  tombs  of  the  present  Czar  and  Czarina  of  Russia 
of  nephrite  from  this  locality. 

In  New  Zealand  nephrite  occurs  in  seve^l  localities  on  the  west  coast 
of  South  Island,  and  is  used  extensively  by  the  Maoris  for  fashioning  into 
weapons  and  ornaments. 

Boulders  of  nephrite  have  also  been  found  in  river  beds  in  Alaska. 
In  several  river  beds  of  Europe  nephrite  is  found  as  pebbles,  and  it  occurs 
in  place  in  the  Zabten  Mountains  in  Silesia,  but  none  of  these  localities 
affords  an  important  source  of  supply. 

Jade,  including  both  jadeite  and  nephrite,  though  still  highly  prized 
by  the  Chinese  and  other  peoples  of  Asia,  is  little  used  by  Europeans  at 

166 


the  present  time.  Among  early  man,  however,  in  Europe,  Asia,  America, 
and  Africa,  the  use  of  jade  seems  to  have  been  well-nigh  universal.  Orna- 
ments and  utensils  of  this  stone  are  found  among  the  remains  of  the  lake 
dwellers  of  Switzerland,  the  ancient  peoples  of  France,  Mexico,  Central 
America,  Greece,  Egypt,  and  Asia  Minor.  The  remarkable  similarity 
in  the  material  from  which  these  objects  are  made,  as  well  as  their 
resemblance  in  form,  has  led  some  authorities  to  conclude  that  they 
came  from  a  single  region,  and  indicate  a  migration  of  people  from  one 
locality  and  a  commerce  in  this  stone.  If  the  evidence  to  this  effect 
were  sufficiently  convincing  it  would  make  possible  many  deductions 
regarding  the  peopling  of  the  globe  of  which  we  have  as  yet  little  certain 
knowledge.  Those  who  oppose  the  view  of  the  distribution  of  jade  from 
a  single  source  declare  that  the  stone  was  found  in  each  different  coun- 
try, and  was  similarly  selected  at  a  certain  stage  in  the  development  of 
each  people.  This  view  seems  to  be  supported  by  the  fact  that  the 
so-called  jade  objects  of  different  peoples  are  not  composed  exclusively 
of  the  two  minerals  above  mentioned,  but  include  any  stone  having  about 
the  same  physical  characters  and  color.  Still,  the  two  minerals  jadeite 
and  nephrite  largely  predominate.  The  two  are  equally  used  by  the 
Chinese  of  the  present  day,  who  do  not  seem  to  distinguish  between  them. 
Their  name  for  jade  is  Yu,  or  Yu-shih  (Yu-stone).  In  general  it  has  been 
found  that  the  peoples  nearer  the  equatorial  zone  of  the  earth  use  more 
jadeite,  and  those  nearer  the  poles  more  nephrite,  but  whether  this  use 
is  anything  more  than  accidental  cannot  be  said. 

The  name  jade  is  from  the  Spanish  piedra  de  hijada,  "  stone  of  the 
loins,"  and  was  given  by  the  Spaniard  Monardas  in  1565  to  the  jade 
brought  from  Mexico  and  Peru  because  these  stones  were  reputed  to  be 
of  value  in  kidney  diseases.  For  this  purpose  it  was  much  worn  as  an 
amulet,  or  taken  internally.  The  name  was  given  the  Latin  form  lapis 
nephriticus  by  Clutius  in  1627,  and  hence  comes  the  word  nephrite. 
Jade  is  also  called  ax-stone  because  of  the  amount  of  it  used  in  making 
these  objects. 

The  Aztecs  applied  the  name  chakhihuitlio  a  greenish  stone  which 
they  used  extensively  and  prized  highly.  This  in  some  instances  proves 
to  be  jade  and  in  others  turquois.  It  is  probable  that  much  of  the 
so-called  emerald  of  ancient  writers  and  historians,  both  of  Europe  and 
America,  was  jade. 


167 


DIOPSIDE 

This  variety  of  pyroxene  affords  transparent  green  stones,  which,  may 
resemble  in  color  chrysolite  or  green  tourmaline.  Diopside  is  common  as 
a  rock-forming  mineral,  but  is  obviously  of  use  for  gem  purposes  only 
when  occurring  in  large,  transparent  crystals.  The  three  localities  where 
material  of  the  latter  sort  is  chiefly  obtained  are  the  Ala  Valley  in  the 
Piedmont  region  of  Italy,  the  Zillerthal  in  the  Tyrolese  Alps,  and  De 
Kalb,  St.  Lawrence  County,  New  York.  The  first  and  third  localities 
afford  light  green  stones,  the  second  those  of  a  dark  bottle-green  color. 
They  are  cut  generally  as  brilliants,  and  while  not  extensively  used,  make 
satisfactory  stones.  Those  obtained  from  De  Kalb  afford  gems  up  to  10 
carats  in  size.  Diopside  may  be  distinguished  from  gems  of  other  min- 
erals of  the  same  color  by  its  lack  of  dichroism,  this  being  a  characteristic 
of  this  pyroxene.  From  glass  it  differs  in  being  doubly  refracting. 
Its  system  of  crystallization  is  monoclinic.  Its  hardness  is  6 ;  specific 
gravity,  3-3.6.  In  composition  diopside  is  a  silicate  of  lime  and  mag- 
nesia, with  a  small  amount  of  iron,  its  color  growing  darker  with  more 
iron.  It  has  a  prismatic  cleavage,  not  often  strongly  enough  developed, 
however,  to  interfere  with  cutting  the  mineral.  Its  luster  is  somewhat 
oily  like  that  of  chrysolite.  The  appearance  of  crystals  from  the  Ala, 
accompanying  essonite,  is  shown  in  the  colored  plate. 


168 


HYPERSTHENE  AND  BRONZITE 

These  minerals,  belonging  to  the  pyroxene  group,  are  employed  in 
jewelry  when,  on  account  of  a  fibrous  structure  or  a  regular  arrangement 
of  inclusions,  they  exhibit  a  chatoyant  effect.  They  do  not  afford  trans- 
parent stones,  but  are  cut  en  cabochon  to  make  cat's-eyes  and  give  other 
schillerizing  effects. 

The  color  of  hypersthene  is  usually  a  dark  bronze,  so  opaque  as  to 
approach  a  metal  in  luster.  The  light  which  plays  over  it  is  copper-red  in 
color,  and  very  brilliant  in  a  good  stone.  The  cause  of  the  chatoyancy 
is  supposed  to  be  countless  crystals  of  the  oxide  of  titanium,  known  as 
brookite,  which  are  arranged  in  regular  order  in  the  stone.  The  stone 
must  be  cut  with  reference  to  the  direction  of  these  in  order  to  give  the 
chatoyant  effect. 

The  hypersthene  used  for  this  purpose  comes  almost  exclusively  from 
the  Island  of  Paul  on  the  coast  of  Labrador.  Here  it  occurs  together 
with  labradorite  as  shore  pebbles,  and  it  may  also  be  quarried  from  neigh- 
boring cliffs.  For  cutting,  a  sound  piece  without  flaws  must  be  used, 
and  it  is  often  necessary  to  break  a  number  of  fragments  before  a  suit- 
able one  can  be  found.  Yet  the  supply  of  material  is  so  abundant  and  the 
demand  comparatively  so  limited  that  the  stones  do  not  command  a  high 
price. 

The  hardness  of  hypersthene  is  5-6;  its  specific  gravity  3.4-3.5.  It 
fuses  before  the  blowpipe  to  a  black  enamel,  and  is  partially  decomposed 
by  hydrochloric  acid.  Its  name  comes  from  two  Greek  words  meaning 
very  tough.  It  is  a  common  constituent  of  eruptive  rocks,  usually  in 
small  crystals.  Its  system  of  crystallization  is  orthorhombic.  In  com- 
position it  is  a  silicate  chiefly  of  iron  and  magnesium. 

Enstatite  resembles  hypersthene  in  composition  and  properties,  and 
its  limited  use  in  jewelry  is  to  furnish  "  cat's-eyes  "  of  a  green  color.  The 
chatoyant  effect  is  due  usually  to  a  fibrous  structure.  The  principal 
locality  for  this  variety  is  near  Harzburg  in  the  Harz.  Schillerizing 
bronzite  is  found  in  a  few  localities  in  this  country. 


169 


TURQUOIS 

This  mineral  differs  from  nearly  all  others  held  in  favor  as  gems 

v)--'^"*'1 

in  not  being  transparent,  and  never-'  occurring  in  the  form  of  well- 
defined  crystals.  In  composition  turquois  is  a  hydrous  phosphate  of 
aluminum,  the  percentages  being:  water,  20.6  per  cent,  alumina,  46.8 
per  cent,  and  phosphorus  oxide,  32.6  per  cent.  Thus,  in  composition 
as  well  as  opacity,  turquois  differs  from  most  other  gems,  they  being 
usually  silicates,  or  some  form  of  silica.  Besides  the  above  ingredients 
turquois  always  contains  a  small  percentage  of  copper  oxide,  and  usually 
iron,  calcium,  and  manganese  oxides  in  small  amount.  It  is  the  copper 
compound  which  undoubtedly  gives  turquois  its  inimitable  color,  that 
color  to  which  it  owes  its  chief  charm  as  a  gem.  This  color  varies  from 
sky-blue  through  bluish  green,  and  apple-green  to  greenish  gray. 

Of  these  colors,  the  pure  sky-blue,  or  robin' s-egg  blue,  is  by  far 
the  most  highly  prized,  and  is,  in  fact,  the  only  standard  color  for  the 
gem.  Green  is,  however,  the  most  common  and  the  most  lasting  color 
of  the  mineral,  and  it  is  one  of  the  faults  of  the  gem  that  the  blue 
shades  often  fade  to  green  after  being  exposed  to  the  light  for  a  time. 
In  a  stone  of  first  quality,  however,  especially  a  Persian  turquois,  such 
fading  of  color  is  exceptional.  The  hardness  of  turquois  is  6.  It  is,  therefore, 
somewhat  more  easily  scratched  than  other  gems.  Its  specific  gravity 
varies  from  2.6  to  2.8,  being  about  that  of  quartz.  It  does  not  fuse 
before  the  blowpipe;  but  turns  brown  and  assumes  a  glossy  appear- 
ance. By  the  copper  of  the  turquois  the  blowpipe  flame  is  usually 
colored  green.  When  heated  in  a  closed  glass  tube  the  mineral  turns 
brown,  or  black,  and  gives  off  water.  Almost  any  of  these  tests  will 
serve  to  distinguish  true  turquois  from  stones  used  to  imitate  it.  It 
has  a  conchoidal  fracture  and  waxy  luster.  On  account  of  its  opacity 
it  is  almost  never  cut  with  facets,  but  in  a  round,  or  oval  form,  with 
convex  surface.  The  pieces  desirable  for  cutting  rarely  reach  a  large 
size,  so  that  big  gems  of  turquois  are  comparatively  unknown. 

Much  of  the  so-called  turquois  used  in  former  times  was  bone-turquois, 
or  odontolite,  made  from  fossil  bone,  colored  by  a  phosphate  of  iron.  It 
is  still  obtained  mostly  from  the  vicinity  of  the  town  of  Simor,  Lower 
Languedoc,  France.  It  is  sometimes  known  as  Western,  or  Occidental 

170  ' 


turquois,  in  distinction  from  the  Oriental  turquois,  most  of  which  came 
originally  from  Persia.  Odontolite  does  not  retain  its  color  by  artificial 
light,  as  does  true  turquois,  and  may  be  further  distinguished  by  giving 
off  an  offensive  odor  when  heated,  owing  to  decomposition  of  animal 
matter.  Further,  it  is  lighter  than  true  turquois,  and  does  not  give 
a  blue  color,  with  ammonia,  when  dissolved  in  hydrochloric  acid,  as  does 
true  turquois. 

txThe  finest  turquoises  have  long  come  from  Persia,  from  a  locality 
not  far  from  Nishapur,  in  the  province  of  Khorassan.  Here  the  min- 
eral occurs  in  narrow  seams,  in  the  brecciated  portions  of  a  porphyritic 
trachyte  and  the  surrounding  clay  slate.  There  are  several  hundred 
mines  in  the  region,  and  the  entire  population  of  the  town  of  Maaden 
derives  its  livelihood  from  mining  and  cutting  the  stones.  It  is  said 
that  $40,000  worth  of  stones  are  taken  from  these  mines  annually. 
A  pound  of  stones  of  the  first  quality  sells  at  the  mines  for  about 
$400,  and  is  worth  more  than  double  that  price  in  Europe.  The  mines 
must  be  very  ancient.  A  description  of  them  written  in  A.  D.  1300 
is  known ;  and  according  to  a  tradition  current  in  the  region  one  of  the 
mines,  known  as  Isaac's  mine,  was  opened  by  Isaac  the  son  of  Abra- 
ham. There  are  other  turquois  mines  in  Persia,  but  their  product 
is  comparatively  small.  Other  Oriental  localities  from  which  gem 
turquoises  are  obtained  are  Sinai,  in  Arabia;  the  Kirgeshi  Steppes, 
in  Siberia;  and  the  Kara-Tube  Mountains,  in  Turkestan.  Egypt  also 
furnishes  large  quantities  of  turquois,  which  does  not,  as  a  rule,  retain 
its  color  well.  I/ 

Turquois  is  not  an  uncommon  mineral  in  the  United  States,  and 
many  gems  of  fine  quality  have  been  obtained  from  mines  within  our 
borders.  The  oldest  and  best  known  mines  are  those  at  Los  Cerrillos, 
New  Mexico.  This  locality  was  long  worked  by  Indians  and  Spaniards, 
as  shown  by  the  great  extent  of  the  excavations.  There  are  pits  to  be 
seen  here  two  hundred  feet  in  depth,  and  piles  showing  that  thousands 
of  tons  of  rock  have  been  broken  out.  Fragments  of  Aztec  pottery, 
vases,  cooking  utensils,  stone  hammers,  etc.,  are  found  at  the  mines, 
and  trees  of  considerable  size  have  grown  over  the  once  worked  portions. 
Hence,  the  beginning  of  the  mine  workings  must  date  back  at  least  prior 
to  the  discovery  of  America.  The  mines  were  worked  more  or  less 
by  Spaniards  in  the  early  part  of  the  seventeenth  century  with  the 
consent  of  the  Indians,  or  at  least  without  hindrance  from  them.  In 
1680,  however,  a  large  landslide  occurred  on  the  mountain  at  the 
mine,  and  many  of  the  Indian  miners  were  overwhelmed.  Believing 
the  Spaniards  to  be  in  some  way  responsible  for  the  accident,  and 

171 


perhaps  fearing  that  their  gods  were  displeased,  the  Indians  rose  in  their 
might  and  expelled  the  Spaniards  from  the  region.  The  Indians  seem  to 
have  prized  the  turquois  highly  as  an  ornament,  rudely  polishing  it,  and 
using  perforated  pieces  like  the  one  shown  in  the  accompanying  colored 
plate  for  necklaces.  They  also  decorated  their  idols  and  other  objects 
of  worship  with  pieces  of  turquois.  The  mountain  at  which  the 
Los  Cerrillos  turquois  mines  occur  is  called  Mount  Chalchihuitl,  in  allu- 


Turquois  mine 
Gem  Turquois  and  Copper  Co.,  Burro  Mountain,  near  Silver  City,  New  Mexico 

sion  to  an  Indian  name  that  is  supposed  to  have  been  applied  to  tur- 
quois. The  mountain  is  evidently  of  volcanic  origin.  The  color  of  most 
of  the  turquois  from  this  locality  is  apple -green  rather  than  the 
highly  prized  blue,  but  some  gems  of  a  good  blue  have  been  obtained. 
Kunz,  writing  in  1890  of  the  sale  of  gems  from  this  locality,  says  that 
the  Indians  usually  dispose  of  them  at  the  rate  of  twenty-five  cents  for 
the  contents  of  a  mouth,  which  is  where  they  usually  carry  them. 
Several  other  localities  in  New  Mexico  are  worked  for  turquois.  In 
Cochise  County,  Arizona,  is  a  locality  known  as  Turquois  Mountain, 
where  considerable  mining  is  carried  on. '  Turquois  is  also  mined  in  Gila 
County,  Arizona ;  Lincoln  County,  Nevada ;  and  San  Bernardino  County, 

172 


California.  Several  of  these  localities  have  been  opened  up  recently, 
the  present  popularity  of  the  gem  perhaps  having  stimulated  its  output. 
Good  New  Mexico  turquoises  are  quoted  at  $5  to  $6  per  carat  at  the 
present  time. 

The  much  higher  price  commanded  by  turquois  of  a  blue  color  has 
led  to  a  counterfeiting  of  this  color  by  staining  green  turquois  or  other 
stones  with  Prussian-blue.  Kunz  describes  a  method  of  detecting  this 
stain  which  consists  in  washing  the  stone  with  alcohol ;  and  after  wiping 
it,  to  remove  any  grease,  laying  it  for  a  moment  in  a  solution  of  am- 
monia, when  the  blue  color,  if  artificial,  will  largely  disappear. 

At  how  early  a  date  turquois  began  to  be  prized  as  a  gem  is  not  known. 
The  word  turquois  is  a  French  word  meaning  Turkish,  or  a  Turkish  gem, 
and  came  to  be  applied  because  the  gem  was  introduced  into  Europe 
by  way  of  Turkey.  It  is  probable  that  the  gem  has  been  in  use  from 
the  remotest  past  among  Oriental  peoples,  and  it  is  certainly  still  highly 
prized  by  them.  Not  the  least  of  the  reasons  for  which  it  is  held  in 
high  esteem  by  them,  as  well  as  by  many  Occidental  individuals,  is  the 
good  fortune  it  is  supposed  to  bring  to  its  possessor.  One  of  the  prov- 
erbs of  the  Orientals  is,  "A  turquois  given  by  a  loving  hand  carries 
with  it  happiness  and  good  fortune."  That  belief  in  the  turquois  as  an 
agent  of  good  luck  was  current  in  Shakespeare's  time  is  shown  by  the 
grief  which  he  represents  Shylock  as  suffering  over  the  loss  of  his 
turquois  ring.  Numerous  other  superstitions  cling  around  the  turquois. 
One  of  these,  due  probably  to  slight  changes  of  color  which  the  stone 
may  undergo  under  certain  climatic  influences,  is  that  if  the  owner  of  a 
turquois  sickens  it  will  grow  pale,  and  at  his  death  lose  its  color  entirely ; 
but  it  will  regain  its  color  if  placed  on  the  finger  of  a  new  and  healthy 
master.  It  was  supposed  to  show  the  presence  of  poisons  by  sweating 
profusely.  It  is  still  used  in  the  East  as  a  remedy  for  dyspepsia,  hernia, 
insanity,  and  cancerous  sores  Worn  as  an  amulet,  it  is  supposed  to 
bring  happiness,  dispel  fear,  and  render  its  wearer  safe  from  drowning, 
lightning,  and  snake  bite.  In  Egypt  it  is  used  to  cure  cataract  if  set  in 
a  silver  ring,  dipped  in  water,  and  applied  to  the  eye  with  proper  incan- 
tations. In  Germany  it  is  hi  favor  for  engagement  rings,  owing  to  the 
belief  that  if  either  party  prove  inconstant  the  stone  will  make  the 
fickleness  known  by  weakening  in  color.  It  is  curious  that  of  the  two 
non-crystallized  gems,  turquois  and  opal,  one  should  be  considered  lucky 
and  the  other  unlucky.  Both  are  more  liable  to  changes  of  color  than 
other  gems,  and  this  fact  has  probably  led  to  the  ascription  of  good 
or  ill  fortune  to  them. 


173 


VARISCITE 

Variscite  resembles  turquois  in  many  properties,  being,  like  that  min- 
eral, an  opaque,  hydrous  phosphate  of  aluminum  not  occurring  in 
distinct  crystals.  Its  color  is,  however,  normally  an  apple-green  to  emer- 
ald-green rather  than  blue,  and  its  luster  is  more  nearly  vitreous  than 
that  of  turquois.  Its  hardness  is  not  equal  to  that  of  turquois,  being 
but  4.  Its  specific  gravity  is  2.4.  It  is  infusible  before  the  blowpipe, 
but  becomes  white  and  colors  the  flame  deep  bluish-green  on  heating. 
The  only  form  of  it  that  has  been  used  to  any  extent  for  gem  purposes 
is  one  found  in  Cedar  Valley,  Tooele  County,  Utah.  This  is  of  a  bright 
green  color,  and  occurs  as  nodules  in  a  crystalline  limestone.  Pieces  of 
this  give  a  pleasing  effect  when  employed  in  jewelry  in  a  manner  similar 
to  turquois. 


CALLAINITE 

This  mineral  has  been  found  only  in  a  Celtic  grove  at  Mani-er-H'rock, 
near  Lockmariaquer,  in  Brittany.  It  is  there  preserved  in  the  form  of 
rounded  pieces  in  size  between  a  flaxseed  and  a  pigeon's  egg,  and  was 
doubtless  employed  by  the  ancient  Celts  as  an  ornamental  stone.  Where 
they  obtained  it  has  never  been  learned.  It  is  a  hydrous  phosphate  of 
aluminum  of  a  green  color,  spotted  with  whitish  and  bluish.  Its  hard- 
ness is  3.5  to  4 ;  specific  gravity  2.5.  It  is  opaque  to  translucent.  On 
account  of  its  historic  (or  prehistoric)  interest  pieces  have  been  cut  and 
used  to  some  extent  in  jewelry ;  but  its  employment  can  obviously  not 
be  extensive  on  account  of  the  small  amount  known.  The  name  cal- 
lainite  comes  from  callais,  a  precious  stone  mentioned  by  Pliny,  the  exact 
nature  of  which  is  not  known,  although  it  is  generally  supposed  to  have 
been  turquois. 


174 


509 


Amazonstone,  crystallized  (Colorado). 

Labradorite,  polished  (Labrador). 

Suustone  (Morway). 


FELDSPAR. 
Aniazonstone,  crystallized  (Colorado). 


Amazonstone  (Colorado). 

Labradi  trite,  polished  (Labrador). 

Moonstone,  polished  Norway). 


FELDSPAR 

Feldspar  is  the  family  name  of  several  minerals  closely  related,  and 
indeed  grading  into  each  other,  but  distinguished  by  mineralogists  by 
separate  specific  terms.  These  minerals  are  all  silicates  of  aluminum, 
with  some  alkali  or  alkali  earth,  having  a  hardness  of  about  6  and  a 
specific  gravity  varying  from  2.5  to  2.7.  They  are  fusible  with  difficulty 
before  the  blowpipe,  crystallize  in  the  monoclinic  or  triclinic  system,  and 
cleave  in  two  well-marked  directions  nearly  or  quite  at  right  angles  to 
each  other.  It  is  this  latter  property,  probably,  which  led  to  the  group- 
ing of  these  minerals  as  spar,  since  this  term  is  applied  in  common  lan- 
guage to  any  minerals  which  break  with  bright  crystalline  surfaces.  The 
term  field  spar,  of  which  feldspar  is  probably  a  corruption,  was  perhaps 
given  the  minerals  of  this  group  because  of  their  widespread  occurrence. 
The  English  spelling  of  the  word  is  felspar.  The  feldspars  form  an  essential 
part  of  nearly  all  eruptive  rocks,  and  by  their  decomposition  produce  clays 
and  other  soils  which  may  harden  into  great  areas  of  sedimentary  rocks. 
They  are  thus  of  great  geological  importance  and  interest.  Usually  the 
white  crystals  to  be  seen  in  an  eruptive  rock  in  contrast  to  the  dark 
green  or  black  of  the  pyroxene  or  hornblende,  or  the  glassy,  nearly 
colorless  quartz,  are  feldspar.  The  feldspar  may,  however,  contain  more 
or  less  iron,  and  then  take  on  a  flesh  color  or  become  even  darker.  Feld- 
spar crystals  can  best  be  recognized  by  their  prominent  cleavage,  which 
appears  as  numerous  bright  flat  surfaces  extending  in  any  given  crystal 
in  the  same  direction.  The  crystals,  while  they  may  be  of  so  minute 
dimensions  as  to  be  visible  only  with  the  microscope,  may,  on  the  other 
hand,  reach  in  veins  in  coarse-grained  granites  a  length  of  a  foot  or  more. 

As  ornamental  stones  only  certain  varieties  of  feldspar  are  valued, 
and  their  value  depends  on  accidents  of  color  or  structure.  The  first  of 
the  feldspars  which  may  be  mentioned  as  being  prized  as  an  ornamental 
stone  is  amazonstone,  or  green  feldspar.  This  in  composition  is  what  is 
called  a  potash  feldspar,  potash  being  the  alkali  which  in  combination 
with  alumina  and  silica  goes  to  make  up  the  mineral.  The  percentages 
of  each  in  a  pure  amazonstone  are,  silica  64.7,  alumina  18.4,  and  potash 
16.9.  The  mineralogical  name  of  the  species  is  microcline,  meaning 
small  inclination,  and  refers  to  the  fact  that  the  angle  between  the  two 

175 


cleavages  of  the  mineral  is  not  quite  a  right  angle.  The  common  color 
of  microcline  is  white  to  pale  yellow,  but  occasionally  green  and  red  occur. 

It  is  only  to  the  green  variety  that  the  name  of  amazonstone  is 
applied,  a  name  meaning  stone  from  the  Amazon  River.  It  first  referred 
probably  to  jade,  or  some  such  green  stone  from  that  locality,  and  then 
came  to  include  green  feldspar.  No  occurrence  of  green  feldspar  in  that 
region  is  now  known. 

Practically  all  the  amazonstone  now  used  for  ornamental  purposes 
comes  from  three  localities.  These  are  the  vicinity  of  Miask  in  the  Ural 
Mountains,  Pike's  Peak,  Colorado,  and  Amelia  Court  House,  Virginia. 
In  all  these  places  the  amazonstone  occurs  in  coarse-grained  granite,  and 
is  accompanied  by  quartz  and  mica.  All  gradations  are  found  in  color 
from  the  deep  green  to  white,  only  the  bright  green  being  prized  for 
ornamental  purposes.  The  feldspar  is  usually  well  crystallized,  and 
crystals  of  several  pounds'  weight  may  be  found.  A  crystal  will  rarely 
be  of  a  uniform  color,  streaks  of  paler  green  or  white  being  commonly 
present.  Only  the  uniformly  colored  portions  are  prized  for  ornamental 
purposes.  The  green  often  takes  on  a  bluish  tone,  and  blue  sometimes 
even  predominates.  The  color  is  doubtless  due  to  some  organic  matter, 
as  it  disappears  on  heating,  leaving  the  stone  white.  The  stone  is  always 
opaque.  Its  use  is  not  extensive,  its  sale  being  chiefly  to  tourists  in 
the  vicinity  of  the  regions  where  it  is  found.  Several  other  localities  in 
the  United  States  besides  those  mentioned  afford  the  mineral,  though  not 
in  large  quantities.  It  occurs  in  two  or  three  localities  in  North  Caro- 
lina; in  Paris,  Maine ;  Mount  Desert,  Maine;  Rockport,  Massachusetts ; 
and  Delaware  County,  Pennsylvania.  The  finest  comes  from  the  Pike's 
Peak  locality.  Kunz  states  that  when  crystals  from  the  latter  locality 
were  first  exhibited  at  the  Centennial  Exposition  in  Philadelphia,  in 
1876,  they  were  a  great  surprise  to  Russian  dealers,  who  had  brought 
over  some  amazonstone  from  the  Urals,  expecting  to  sell  it  at  what 
would  now  be  considered  fabulously  high  prices. 

The  second  species  of  feldspar  which  may  be  mentioned  as  of  use  as 
an  ornamental  stone  is  labradorite.  This  differs  in  composition  from 
amazonstone  in  containing  soda  and  lime  in  place  of  potash,  the  percent- 
ages in  a  typical  labradorite  being,  silica  53.7,  alumina  29.6,  lime  11.8, 
and  soda  4.8.  Labradorite  has  the  typical  cleavage  of  feldspar  and 
cleavage  surfaces  in  the  direction  of  easiest  cleavage  are  usually  marked 
by  rows  of  parallel  striae.  These  show  that  the  mass  is  made  up  of  a 
series  of  crystal  twins  in  parallel  position,  and  afford  an  excellent  crite- 
rion for  determining  a  triclinic  feldspar.  Labradorite  is  a  common 
rock-forming  mineral,  especially  in  the  older  rocks.  It  is  only,  how- 

176 


ever,  when  it  occurs  in  large  pieces  which  exhibit  a  play  of  colors  that  ' 
it  is  prized  as  an  ornamental  stone.  The  labradorite  exhibiting  the  latter 
property  in  the  most  remarkable  degree  and  hence  most  valued  is  that 
found  on  the  coast  of  Labrador  near  Nain,  and  the  adjacent  Island  of 
St.  Paul.  It  was  first  found  here  by  a  Moravian  missionary  named  Wolfe, 
and  brought  to  Europe  in  the  year  1775.  It  occurs  together  with  hy- 
persthene,  in  a  coarse-grained  granite,  or  perhaps  a  gneiss.  From  these 
it  is  weathered  out  by  wave  and  atmospheric  action,  and  occurs  as  beach 
pebbles.  It  is  also  mined  from  veins.  Labradorite  of  pleasing  color  and 
opalescence  occurs  in  a  few  localities  in  Canada,  and  in  Essex  County,  New 
York.  Two  localities  occur  in  Russia,  one  near  St.  Petersburg,  and  the  other 
in  the  region  of  Kiew.  The  labradorite  of  the  latter  locality  is  the  better, 
its  occurrence  being  in  a  coarse-grained  gabbro.  The  Labrador  occur- 
rence exceeds  all  others,  however,  in  abundance  and  beauty,  and  by  far 
the  larger  quantity  used  in  the  arts  comes  from  there.  The  play  of 
colors  which  gives  labradorite  its  attractiveness  is  rarely  seen  to  advan- 
tage except  upon  a  polished  surface,  but  whether  polished  or  unpolished, 
it  only  appears  when  the  surface  is  held  at  a  particular  angle  with  refer- 
ence to  the  eye.  Emerson  thus  describes  it  in  his  essay  on  "  Experience," 
"  A  man  is  like  a  bit  of  Labrador  spar,  which  has  no  luster  as  you  turn  it 
in  your  hand,  until  you  come  to  a  particular  angle ;  then  it  shows  deep 
and  beautiful  colors." 

The  play  of  colors  seen  in  labradorite  is  not  like  that  of  the  opal, 
which  presents  to  the  eye  fragments  of  different  colors  varying  in  differ- 
ent positions,  but  appears  as  broad  surfaces  of  a  single  color.  It  is  only 
rarely  that  these  colors  change  with  a  change  of  position.  The  colors 
over  any  given  surface  are  not  usually  alike,  but  more  than  two  or  three 
tints  are  rare.  Each  tint  is  uniform  where  it  occurs,  but  a  tinted  surface 
may  be  interspersed  with  many  spots  exhibiting  no  sheen.  Both  colored 
and  uncolored  portions  have  only  vague  outlines,  and  merge  into  each 
other  at  the  edges.  Bauer  mentions  a  labradorite  from  Russia  the  col- 
ored portions  of  which  formed  a  striking  likeness  of  Louis  XVI.,  the 
head  being  a  beautiful  blue  against  a  gold-green  background,  while  above 
appears  a  beautiful  garnet-red  crown.  Excellent  effects  are  sometimes 
produced  in  labradorite  by  cutting  it  in  the  form  of  cameos  so  as  to 
make  the  base  of  different  color  from  the  figure  in  relief.  Because  of  its 
chatoyancy  labradorite  is  sometimes  known  as  "  ox-eye,"  or  "  ceil-de-bceuf." 
Of  the  different  colors  shown  by  labradorite  blue  and  green  are 
most  common,  yellow  and  red  least  so.  These  colors  are  regarded  by 
Vogelsang  as  of  different  origin,  the  blue  being,  in  his  opinion,  a  polariza- 
tion phenomenon  due  to  the  lamellar  structure  of  the  feldspar,  and  the 

177 


yellows  and  reds   the   result  of   the  reflection  of   light    from   minute 
included  crystals  of  magnetite,  hematite,  and  ilmenite. 

The  gems  known  as  moonstone  and  sunstone  owe  the  play  of  colors 
which  gives  them  their  respective  names  to  similar  causes.  These  gems 
are  generally  some  form  of  feldspar,  although  any  mineral  giving  a 
similar  sheen  of  color  might  be  included  under  them.  The  moonstone 
of  commerce  comes  chiefly  fromkCeylon,  where  it  occurs  in  large  pieces 
the  size  of  a  fist  in  a  clay  resulting  from  the  decomposition  of  a  por- 
phyritic  rock.  Pieces  of  these  when  polished  exhibit  a  beautiful  pale 
blue  light  coming  from  within,  which  makes  the  stone  prized  as  a  gem. 
The  cause  of  this  light  has  usually  been  thought  to  be  reflection  from 
minute  tabular  crystals  lying  in  parallel  position  in  the  stone.  It  seems 
to  be  partly  caused  also  by  absorption  of  red  and  yellow  rays  by  the  stone, 
leaving  the  violet  and  blue  to  be  reflected  and  diffused. 

Moonstone  varies  from  translucent  to  opaque,  and  from  colorless  to 
white,  the  essential  feature  being  the  blue  opalescent  light  or  chatoyancy 
exhibited  from  a  polished  surface.  Good  feldspar  moonstones  are  worth 
from  three  to  five  dollars  a  carat. 

The  Ceylon  moonstone  is  sometimes  known  as  Ceylon  opal,  but  it 
is  not  opal.  On  the  contrary,  it  is  the  variety  of  feldspar  known  as 
orthoclase,  which  is  a  potash  feldspar,  differing  from  the  microcline 
just  described  in  being  monoclinic  in  crystallization  and  in  having  two 
cleavages  meeting  at  right  angles.  Another  species  of  feldspar  used  as 
,  moonstone  is  albite.  This  is  a  soda  feldspar,  and  is  triclinic,  but  exhibits 
the  chatoyancy  characteristic  of  moonstone.  One  variety  is  known  as 
peristerite,  from  the  Greek  word  for  pigeon,  and  is  applied  on  account 
of  the  resemblance  of  the  sheen  to  that  of  a  pigeon's  neck.  It  is  found 
t^at  Macomb,  St.  Lawrence  County,  New  York.  Albite  found  at  Mineral 
Hill,  Pennsylvania,  also  exhibits  the  chatoyancy  of  moonstone.  Amelia 
Court  House,  Virginia,  is  another  locality  whence  come  pieces  either  of 
orthoclase  or  oligoclase  exhibiting  this  property.  Like  most  of  the  more 
or  less  opaque  gems,  moonstone  is  cut  chiefly  in  the  cabochon  form.  It 
is  of  late,  however,  cut  in  the  form  of  balls,  which  are  quite  popular,  the 
bringing  of  good  luck  being  attributed  to  them.  The  brilliancy  of  moon- 
stone is  considerably  increased  by  mounting  it  against  black. 

In  the  Middle  Ages  carrying  a  moonstone  in  the  mouth  was  believed 
to  be  an  aid  to  the  memory.  It  was  prescribed  in  cases  of  epilepsy, 
either  as  an  amulet  or  powder.  Belief  in  its  efficacy  for  this  purpose  still 
persists  among  the  Basques.  During  the  period  of  increase  of  the  moon 
it  was  regarded  a  potent  love  charm,  while  during  the  decrease  of  that 
luminary  it  was  supposed  to  enable  its  wearer  to  foretell  the  future. 

178 


Sunstone  is  the  term  by  which  those  kinds  of  feldspar  are  known 
which  reflect  a  spangled  yellow  light.  The  appearance  comes  from  minute 
crystals  of  iron  oxide,  hematite,  or  gothite,  which  are  included  in  the 
stone,  and  which  both  reflect  the  light  and  give  it  a  reddish  color.  Like 
labradorite  the  sheen  is  visible  only  when  the  stone  is  held  at  a  certain 
angle.  The  sheen  of  sunstone  is  best  visible  when  the  stone  is  held  in  the 
sunlight  or  strong  artificial  light.  The  variety  of  feldspar  to  which  the 
sunstone  most  in  use  at  the  present  time  belongs  is  oligoclase,  a  soda-lime 
triclinic  feldspar.  Like  labradorite,  it  usually  exhibits  on  the  surface  of 
easiest  cleavage  parallel  striations,  due  to  twinning  structure.  The  best 
sunstone  at  the  present  time  comes  from  Tvedestrand,  in  southern  Norway, 
where  it  occurs  in  compact  masses,  together  with  white  quartz,  in  veins 
in  gneiss.  Some  also  comes  from  Hittero,  Norway.  In  Werchne  Udinsk, 
Siberia,  another  occurrence  was  discovered  in  1831.  Previous  to  this 
Bauer  states  that  all  the  sunstone  known  came  from  the  Island  of  Sattel 
in  the  White  Sea,  and  was  very  costly,  although  of  a  quality  which  would 
not  now  be  deemed  desirable.  At  the  present  time,  although  stones  of 
fine  quality  can  be  obtained,  sunstone  is  little  used  in  jewelry,  and  its 
market  value  is  very  low.  Statesville,  North  Carolina,  and  Delaware 
County,  Pennsylvania,  are  two  localities  in  the  United  States  where  good 
sunstone  has  been  obtained. 

Both  sunstone  and  moonstone  can  be  accurately  imitated  in  glass, 
and  the  distinction  of  the  artificial  from  the  real  by  ocular  examination 
alone  might  be  somewhat  difficult.  Glass,  however,  lacks  the  cleavage 
of  feldspar,  and  is  somewhat  heavier  and  softer.  The  discovery  of  the 
method  of  making  artificial  sunstone  is  said  to  have  been  accidental,  and 
was  made  at'Murano,  near  Venice,  when  a  quantity  of  brass  filings  by 
chance  fell  into  a  pot  of  melted  glass.  The  product  was  for  a  long  time, 
and  is  still,  used  in  the  arts  under  the  name  of  goldstone.  Sunstone  is 
sometimes  known  as  aventurine  feldspar,  in  distinction  from  aventurine 
quartz,  which  presents  a  similar  appearance,  owing'  to  the  inclusion  of 
scales  of  mica.  The  term  aventurine  is  from  the  Italian£xziwm£wra, 
meaning  chance,  and  refers  to  the  chance  discovery  above  referred  to. 
Other  forms  of  feldspar  than  those  here  described  occasionally  furnish 
gems  which  are  transparent  and  colorless,  and  valued  for  their  luster. 
The  varieties  chiefly  employed  in  this  manner,  are  adularia,  a  variety  of 
orthoclase  which  is  often  transparent,  the  best  specimens  being  obtained 
in  Switzerland,  and  oligoclase,  in  the  transparent  form  in  which  it  is 
found  near  Bakersville,  North  Carolina. 


179 


OBSIDIAN 

This  is  a  natural  glass  which  is  used  to  some  extent  at  the  present 
day  for  ornamental  purposes.  In  earlier  times,  especially  among  the 
prehistoric  peoples  of  the  western  hemisphere,  its  use  was  very  exten- 
sive, both  for  utensils  and  ornamental  articles. 

Obsidian  is  a  product  of  volcanic  outflows,  being  produced  where 
a  rapid  cooling  of  certain  liquid  lavas  has  taken  place.  In  color  it 
may  be  black,  gray,  green,  red,  brown,  or  yellow,  and  in  diaphaneity 
may  vary  from  transparent  to  opaque.  The  kind  used  almost  exclu- 
sively in  the  arts  is  of  black  color,  generally  transparent  only  in  thin 
pieces. 

The  properties  of  obsidian  differ  little  from  those  of  manufactured 
glass.  Its  hardness  is  5-5^;  specific  gravity  2.3-2.5.  It  has  a  vitreous 
luster,  and  is  brittle,  breaking  with  a  large  conchoidal  fracture  which 
is  quite  noticeable.  Its  extreme  brittleness  makes  cutting  of  it  difficult. 
It  fuses  rather  easily  before  the  blowpipe  to  a  porous,  gray  mass. 
Being  amorphous  it  cannot  be  distinguished  optically  from  glass,  like 
which  it  is  singly  refracting.  It  frequently  contains  partially  crystal- 
lized inclusions,  however,  and  gas  pores,  which  are  not  common  to  arti- 
ficial glass.  When  these  ,are  arranged  in  regular  order  the  obsidian 
shows  a  chatoyancy,  or  schillerization,  which  gives  a  pleasing  effect. 
In  chemical  composition  obsidian  shows  a  higher  percentage  of  alumina 
and  a  lower  one  of  alkalies  than  artificial  glass.  The  following  is  the 
composition  of  an  obsidian  from  the  Lipari  Islands:  Silica,  74.05, 
alumina,  12.97,  iron  oxide,  2.73,  lime,  0.12,  magnesia,  0.28,  potash, 
5.11,  soda,  3.88,  loss  on  ignition,  0.22.  Obsidian  is  not  easily  attacked 
by  acids.  One  of  the  largest  known  deposits  of  obsidian  in  this  coun- 
try occurs  in  the  Yellowstone  Park,  Wyoming.  The  locality  is  known 
as  Obsidian  Cliff,  and  the  deposit  has  a  thickness,  according  to  Profes- 
sor Iddings,  of  75  to  100  feet.  There  are  evidences  that  the  Indians 
obtained  obsidian  here  for  use  in  their  arts,  as  flaked  fragments  are 
found  in  the  vicinity.  The  color  of  this  obsidian  is  for  the  most  part 
black,  but  shades  of  red  and  yellow  occur. 

A  variety  of  obsidian,  showing  red  and  black  in  alternate  streaks, 
or  spots,  occurs  here  as  well  as  in  other  localities.  This  is  known  as 

180 


marekanite,  or  "  mountain  mahogany,"  and  makes  a  pretty  stone,  which 
is  used  for  the  manufacture  of  some  objects. 

The  mines  from  which  the  Aztecs  and  their  successors  seem  to  have 
obtained  the  greater  part  of  their  obsidian  are  located  in  the  State 
of  Hidalgo,  Mexico,  about  thirty  miles  east  of  Pachuca.  The  locality 
is  known  as  the  Sierra  de  las  Navajas,  or  Hill  of  the  Knives.  Here 
hundreds  of  acres  have  been  worked  over,  and  heaps  and  ridges  of  obsidian 
fragments  are  continuous  for  one  or  two  miles.  The  mining  seems  to  have 


Obsidian  cliff,  Yellowstone  Park 

been  performed  by  digging  pits  from  6  to  20  feet  in  depth.  Large  pieces 
of  obsidian  were  thus  obtained,  which  were  shaped  into  so-called  cores, 
cylindrical  pieces  of  varying  diameters.  From  these,  articles  of  the 
desired  shape  were  obtained  by  flaking  and  polishing.  Immense  heaps 
of  flakes  show  that  working  of  the  obsidian  was  carried  on  here  for 
centuries.  Articles  made  from  it  are  found  among  the  Aztec  ruins  in 
Mexico,  and  as  far  north  as  the  mounds  of  Ohio.  They  are  of  great 
variety,  and  many  of  them  exhibit  much  skill  in  workmanship.  They 
include  masks,  ear  ornaments,  lip  ornaments,  spear  heads,  arrow  heads, 
knives,  and  razors.  Mirrors  were  also  made  from  the  obsidian.  To  this 
latter  use  obsidian  was  put  by  the  Romans  in  the  time  of  Pliny.  They 

181 


also  manufactured  ring  stones,  seals,  and  other  ornaments  from  it.  The 
source  of  their  obsidian  was  probably  the  island  of  Lipari,  for  exten- 
sive fields  of  beautiful  obsidian  are  still  known  and  worked  there. 
It  also  occurs  in  the  neighboring  islands. 

Its  use  at  the  present  time  is  chiefly  for  making  mourning  jewelry 
it  being  preferred  by  some  to  jet.  Obviously,  it  can  be  closely  imitated 
in  glass;  and  though  the  cost  of  cut  obsidian  is  small,  glass  is  still 
cheaper.  The  schillerizing,  or  chatoyant  obsidian,  is  more  highly  prized 
than  the  plain,  and  cut  en  cabochon  it  makes  a  very  pretty  ring  stone. 
Obsidian  is  sometimes  called  Iceland  agate,  perhaps  because  obtained 
in  Iceland,  although  by  some  it  is  thought  that  the  name  is  a  corrup- 
tion of  island  agate,  from  the  occurrence  of  the  stone  in  the  islands 
of  the  Mediterranean. 


182 


OF  THE 

(    UNIVERSITY  j 

or 


590 


ChlorastroHte,  polished  (Isle  Royale). 
Hematite,  polished  (England). 

Thoiusouite,  polished  (Lake  Superior). 


MINOR  GEMS. 
Cat's-eye,  Quartz,  polished  (Ceylon). 


Variscite,  polished  (Utah). 

Moldavite,  cut  (Bohemia). 
Thomsonite,  rough  (Lake  Superior). 


MOLDAVITE 


This  term  is  applied  to  a  transparent  green  stone  found  occurring 
in  small  pieces  in  Bohemia,  in  the  region  drained  by  the  river  Moldau, 
whence  the  name  moldavite.  The  color  of  the  stone  is  of  the  peculiar 
character  generally  designated  as  bottle-green;  and  since  its  physical 
characters,  such  as  hardness,  fracture,  optical  qualities,  etc.,  also  resemble 
those  of  glass,  the  view  was  long  held  that  the  fragments  found  were 
remains  from  some  long  since  demolished  glass  works.  Latterly,  however, 


Moldavite  pebbles  as  found 


Dr.  Franz  Suess  has  advanced  the  opinion  that  the  fragments  are  of  extra- 
terrestrial origin,  and  represent  a  peculiar  kind  of  meteorite.  These 
views  he  has  set  forth  in  an  elaborate  work  upon  the  subject. 

Proof  of  such  an  origin  of  moldavite  would  lend  an  added  interest 
to  it,  and  probably  increase  its  use  for  jewelry,  the  present  employ- 
ment of  it  being  rather  limited.  The  pieces  as  found  are  waterworn 
pebbles  of  various  shapes,  usually  with  deeply  indented  or  pitted  sur- 
faces, as  shown  in  the  accompanying  cut.  In  size  they  are  never 
larger  than  one's  fist,  while  they  are  usually  much  smaller.  They  are 
found  in  the  beds  of  brooks  and  in  the  soil.  Regions  near  Budweis 
and  Trebitsch  are  especially  prolific  in  the  pebbles.  Moldavite  has  a 
hardness  not  quite  equal  to  that  of  feldspar,  being  a  little  less  than  6. 

183 


It  is  thus  somewhat  harder  than  ordinary  glass.  Its  specific  gravity 
ranges  from  2.32  to  2.36.  Unlike  ordinary  glass  and  obsidian  it  is 
almost  infusible  before  the  blowpipe,  and  when  fused  remains  perfectly 
clear  on  cooling.  It  differs  considerably  in  chemical  composition  from 
ordinary  glass,  having  as  it  does  a  higher  percentage  of  silica,  consider- 
able alumina,  and  a  small  percentage  of  alkalies.  The  percentages  of  silica 
range  between  88  per  cent  and  78  per  cent ;  those  of  alumina  between  5 
per  cent  and  13  per  cent ;  and  those  of  potash  and  soda  between  1  per 
and  2.5  per  cent.  The  following  is  an  analysis  of  a  dark  green  moldavite 
from  Budweis:  Silica,  77.75,  alumina,  12.90,  iron  protoxide,  2.60,  lime, 
3.05,  magnesia,  0.22,  potash,  2.58,  soda,  0.26,  water,  0.10.  In  ordinary 
glass  the  percentage  of  silica  is  not  much  above  50  per  cent ;  there  is 
almost  no  alumina,  while  lime  and  magnesia  amount  to  about  20  per 
cent,  and  potash  and  soda  20  per  cent  to  25  per  cent. 

Glassy  pebbles  similar  to  moldavite  are  found  on  the  island  of  Billiton, 
near  Java.  These  are  known  as  billitonite.  They  are  also  found  in 
Borneo  and  several  parts  of  Australia.  In  these  places  they  are  believed 
to  be  of  volcanic  origin  if  not  meteoric. 

Of  these  different  occurrences  of  moldavite  only  the  Bohemian  is  so 
far  used  to  any  extent  in  jewelry.  Owing  to  the  abundance  of  the  mate- 
rial the  stones  cut  from  it  are  not  expensive,  being  valued  at  no  more 
than  quartz  or  agate.  Actual  glass  can  easily  be  substituted  for  it 
with  little  chance  of  detection. 


184 


APATITE 

This  common  and  widely  distributed  mineral  occasionally  affords 
transparent  crystals  which  admit  of  limited  use  in  jewelry.  The  cut 
stones  cannot,  however,  endure  much  wear,  as  the  hardness  of  the 
mineral  is  only  5.  The  colors  which  the  crystals  may  present  are 
violet,  light  blue,  yellow,  rose,  and  various  shades  of  green.  One  color 
and  degree  of  transparency  may  characterize  an  entire  crystal,  or  but 
a  portion  of  one.  The  crystals  have  nearly  always  the  shape  of  a  simple 
hexagonal  prism,  the  mineral  crystallizing  in  the  hexagonal  system. 
In  composition  apatite  is  phosphate  of  lime,  with  a  small  percentage 
of  fluorine  or  chlorine.  It  is,  therefore,  much  like  bone  in  constitu- 
tion. It  is  barely  fusible  before  the  blowpipe.  On  moistening  a  frag- 
ment with  sulphuric  acid,  and  heating,  the  flame  is  colored  pale  green 
from  the  phosphorus  present.  Apatite  is  attacked  and  dissolved  by 
strong  acids.  Its  specific  gravity  is  3.17-3.23.  Its  luster  is  vitreous 
to  subresinous. 

The  best  known  transparent  apatite  is  obtained  at  Ehrenfriedersdorf, 
in  Saxony.  Here  transparent  crystals  of  a  violet  color  occur  capable 
of  affording  cut  stones  of  a  few  carats  in  weight.  From  Arendal, 
Norway,  greenish-blue  crystals  are  obtained,  furnishing  the  variety  known 
as  moroxite.  A  yellowish  -  green  variety,  known  as  asparagus  stone, 
comes  from  Murcia,  Spain.  At  Mount  Apatite,  Auburn,  Maine,  crystals 
of  pink,  green,  and  violet  colors  have  been  obtained  which  sufficiently 
resembled  tourmaline  to  be  mistaken  for  it. 

Apatite  occurs  most  commonly  in  metamorphic  crystalline  rocks, 
especially  limestone.  It  is  also  found  in  granites  and  mica  schists, 
and  in  sedimentary  rocks ;  but  in  the  latter  it  is  usually  an  amorphous 
mineral. 


185 


FLUORITE,  OR  FLUORSPAR 


Few  if  any  minerals  exceed  this  in  beauty  and  variety  of  colors.  In 
transparency  and  luster  also  it  leaves  little  to  be  desired.  Yet  its  soft- 
ness and  brittleness  are  such  that  it  can  have  but  a  limited  use  for  gem 
purposes.  In  color  it  imitates  closely  many  of  the  well-known  gems,  and 
cut  fluorites  are  often  designated  as  "false"  emerald,  ruby,  amethyst, 
topaz,  etc.  From  genuine  stones  of  these  names  fluorite  can  readily  be  dis- 
tinguished by  its  relative  softness.  Its  hardness  is  4  in  the  scale,  and  it  is 
therefore  readily  scratched  by  a  knife-blade  or  a  piece  of  glass.  Fluorite 

crystallizes  in  the  isometric 
system,  and  has  an  eminent 
cleavage  parallel  to  the  faces 
of  the  octahedron.  This  cleav- 
age is  so  strongly  developed 
that  it  is  difficult  in  cutting 
the  mineral  to  prevent  cracks 
starting  and  portions  breaking 
off.  The  cleavage  also  pro- 
duces flaws  in  the  stones. 
Crystals  of  fluorite  generally  have  the  form  of  simple  cubes.  These 
cubes  are  sometimes  modified  by  other  forms,  and  twinned  cubes  are 
not  uncommon.  One  of  the  most  unique  and  pleasing  properties  of 
fluorite  is  that  known  as  fluorescence.  When  pieces  of  the  mineral  are 
heated  gently  their  interiors  light  up  with  a  bright  glow,  usually  colored, 
and  this  color  is  quite  independent  of  that  of  the  mineral — a  blue  fluorite, 
for  instance,  often  exhibiting  an  emerald-green  fluorescence,  a  green 
stone,  a  purple,  and  so  on.  Sometimes  the  heat  of  the  hand,  or  the 
striking  of  two  pieces  together,  is  sufficient  to  excite  this  glow,  and  an 
increase  of  heat  may  cause  it  to  change  color.  If  heated  too  highly  or 
too  long  the  mineral  loses  both  this  property  and  its  inherent  color.  The 
cause  both  of  the  color  and  the  fluorescence  is  undoubtedly  hydrocarbons 
which  exist  in  the  mineral. 

Fluorite  is  a  simple  fluoride  of  calcium,  having  the  percentage  com- 
position fluorine  48.9,  and  calcium  51.1.  It  fuses  rather  easily  before 
the  blowpipe  to  a  white  enamel,  which  gives  an  alkaline  reaction.  Its 

186 


Crystal  forms  of  fluorite 


specific  gravity  ranges  from  3  to  3.25.  Besides  the  transparent  crystal- 
lized forms,  it  is  found  in  fibrous  and  granular  masses.  It  is  a  common 
mineral,  and  widely  distributed.  Its  most  common  occurrence  is  in  veins 
accompanying  ores  of  lead,  silver,  etc.  It  also  forms  beds.  The  locali- 
ties affording  the  best  known,  and  in  many  respects  the  finest,  fluorite 
are  Cumberland  and  Derbyshire,  England.  In  these  localities  the  fluorite 
is  known  by  the  name  of  Blue  John,  or  Derbyshire  spar,  and  is  worked 
to  some  extent  into  large  ornamental  objects,  such  as  table-tops,  vases, 
etc.  These  articles  are  turned  on  lathes,  the  stone  being  first  soaked  in 
gum-water,  or  similar  adhesive,  to  prevent  its  falling  apart.  One  of  the 
finest  pieces  of  this  sort  of  work  ever  executed  is  to  be  seen  in  the 
Museum  of  Practical  Geology,  London.  This  object  is  a  vase  2  feet 
8  inches  high,  and  3  feet  7  inches  in  its  greatest  circumference.  It  was 
made  by  Mr.  Vallance,  of  Matlock,  from  several  pieces  of  fluorite  occur- 
ring near  Castleton,  in  Derbyshire. 

The  mining  district  of  Saxony  affords  large  quantities  of  fluorite. 
Red  is  one  of  the  rarest  colors  exhibited  by  this  mineral,  and  red  fluorite 
comes  almost  exclusively  from  the  St.  Gothard,  Switzerland. 

In  our  own  country  many  deposits  of  fluorite  occur,  though  little  use 
is  made  of  them  for  ornamental  purposes.  ^-Macomb,  New  York,  has 
furnished  a  large  quantity  of  green  crystals,  exceeding  in  size  and  equal- 
ing in  color  any  ever  found.  An  extensive  deposit  of  fluorite  in  Illinois 
is  mined  for  use  as  a  flux,  but  the  crystals  are  rarely  clear  enough  for 
ornamental  use. 


187 


Hematite  is  an  oxide  of  iron  occurring  in  nature  which  takes  on  a 
variety  of  forms  and  shades,  but  is  used  in  jewelry  only  when  compact 
and  of  an  iron-black  color.  In  this  form  it  is  used  especially  for  in- 
taglios, but  also  for  carving  into  ornaments  of  various  sorts.  Its  hardness 
is  6,  and  specific  gravity  4.9-5.3.  Its  composition  is,  iron  70  per  cent, 
and  oxygen  30  per  cent.  While  in  a  mass  it  is  invariably  opaque,  and 
often  black  in  color ;  in  a  thin  splinter  it  may  be  seen  to  be  slightly  trans- 
lucent and  red.  This  red  color  always  characterizes  the  powder  or  streak 
f  hematite,  and  is  one  of  the  surest  means  of  identifying  the  mineral. 
'As  the  color  resembles  that  of  blood,  the  Greeks  believed  the  mineral  to 
be  concreted  blood,  and  the  name  hematite  is  from  their  word  for  that 
substance.  Under  the  name  of  bloodstone  it  was  long  believed  to  be  a 
curative  of  hemorrhages,  and  Robert  Boyle,  the  eminent  physicist,  writing 
as  late  as  1672,  gravely  relates  a  cure  of  a  case  of  nasal  hemorrhage  of 
long  standing  through  wearing  a  bloodstone  about  the  size  of  a  hen's 
egg  about  the  neck. 

Powdered  hematite  forms  the  rouge  of  commerce  used  so  extensively 
for  polishing. 

Hematite  was  used  in  the  carved  form  by  the  ancients  as  well  as  the 
moderns,  a  number  of  cut  pieces  having  been  found  in  the  ruins  of  Baby- 
lon. Intaglios  of  it  have  also  come  down  to  us  from  the  Romans.  Large 
polished  surfaces  of  hematite  make  excellent. mirrors,  and  frequent  use  was 
made  of  it  for  this  purpose  in  earlier  times.  Hematite  is  so  abundant 
over  the  earth's  surface  that  it  has  little  intrinsic  value  except  as  an  ore 
of  iron.  That  used  in  jewelry  comes  largely  from  northern  Spain.  Hem- 
atite of  a  similar  character  is  obtained  in  the  Island  of  Elba,  Cumberland, 
England,  and  in  the  Lake  Superior  region  of  our  own  country.  Besides 
its  use  for  seals,  it  is  employed  to  make  imitation  black  pearls.  Certain 
fibrous  occurrences  of  hematite  when  cut  in  rounded  forms  give  a  star- 
like  appearance  similar  to  that  exhibited  by  star  sapphires. 


188 


PYRITE 

Pyrite,  also  known  as  marcasite  by  jewelers,  is  a  brass-yellow  min- 
eral with  metallic  luster,  employed  to  some  extent  for  purposes  of  orna- 
ment. It  is  widely  distributed  in  the  earth's  crust,  and  from  its  yellow 
color  and  metallic  luster  is  often  mistaken  for  gold.  A  common  name 
for  it,  therefore,  is  "  fool's  gold."  In  composition  it  is  a  sulphide  of  iron, 
the  percentages  being,  sulphur  53.4  and  iron  46.6.  Its  hardness  is  a  little 
below  that  of  quartz,  or  6^.  The  name  pyrite  is  from  the  Greek  word 


Crystal  forms  of  pyrite 

for  fire,  and  was  given  in  allusion  to  the  fact  that  owing  to  its  hard- 
ness it  will  strike  fire  with  steel.  It  is  heavy,  its  specific  gravity  being 
five  times  that  of  water.  It  is  quite  brittle.  It  crystallizes  in  the  iso- 
metric system,  crystals  of  cubic  or  cuboidal  forms  being  the  most  com- 
mon. Owing  to  its  abundance  in  nature  it  has  practically  110  intrinsic 
value  except  in  large  quantities,  in  which  case  it  forms  an  ore  of  sulphur. 
When  cut  into  various  objects  of  ornament,  however,  it  has  quite  a 
pleasing  effect,  and  at  times  has  been  much  in  favor.  It  is  used  for 
ornamenting  bracelets,  brooches,  scarf-pins,  and  the  like,  and  in  certain 
forms  in  rings. 

For  these  purposes  it  has  usually  been  artificially  facetted,  thus  dis- 
playing its  brilliant  luster.  An  American  firm  has  recently,  however, 
employed  the  pyrite  found  in  the  form  of  a  coating  of  small,  bright 
crystals,  nearly  uniform  in  height,  for  use  in  jewelry.  These  coatings 
are  obtained  from  beds  of  anthracite  coal,  and  only  require  smoothing 
on  the  back  and  cutting  into  pieces  of  suitable  size  and  shape  to  be 
made  available. 

One  of  the  drawbacks  to  the  use  of  pyrite  in  this  way  is  its  easy 
liability  to  tarnish,  and  the  difficulty  afterwards  of  restoring  the  original 
luster.  Some  groups  of  crystals  will  remain  bright  a  long  time  while 

189 


others  tarnish  rapidly.  This  is  especially  true  of  marcasite,  the  ortho- 
rhombic  form  of  iron  sulphide,  which  is  sometimes  confounded  with 
pyrite.  This  even  decomposes  and  crumbles  away  in  time. 

Pyrite  was  used  to  quite  an  extent  in  earlier  times  for  mirrors, 
large  pieces  of  it  being  ground  and  polished  until  they  gave  a  good 
polish.  Among  the  remains  of  the  Incas  of  Peru  have  been  found 
large  numbers  of  these  pyrite  mirrors. 


190 


CHLORASTROLITE 

f  This  mineral,  the  name  of  which  means  "  green-star  stone,"  is  solely 
of  American  occurrence,  and  thus  far  has  been  found  at  but  a  single 
locality.  It  occurs  at  Isle  Royale,  an  island  in  Lake  Superior,  in  the 
form  of  beach  pebbles.  These  pebbles  come  from  the  adjoining  amygda- 
loidal  trap  rock,  out  of  which  they  weather.  They  are  opaque,  and 
of  light,  bluish-green  color,  with  a  mottled  effect  arising  from  a  stel- 
lated or  radiated  structure.  This  structure,  when  the  stone  is  polished, 
affords  a  chatoyancy  which  is  very  pleasing.  It  is  especially  desirable 
in  a  good  stone  that  the  radiation  should  emanate  from  the  center, 
in  which  case  a  cat's-eye  effect  is  obtained.  The  pebbles  which  make 
good  stones  are  mostly  small;  but  some  an  inch  in  diameter  are 
known.  The  hardness  of  the  mineral  is  5.5,  and  its  specific  gravity 
3.18.  It  is  not  a  homogeneous  mineral  but  a  mixture,  composed 
chiefly  of  a  hydrous  aluminum  silicate.  The  stones  have  not  attained 
extensive  use  as  yet,  except  as  they  are  sold  in  quantities  to  tourists  in 
the  Lake  Superior  region,  i/ 


191 


THOMSONITE 

(MESOLITE.) 

6/iAn  occurrence  of  this  mineral,  which  is  used  ornamentally  to  some 
extent,  is  obtained,  like  chlorastrolite,  in  the  form  of  waterworn  pebbles 
weathered  out  of  an  amygdaloidal  trap.  The  pebbles  are  found  on 
the  shores  of  Lake  Superior,  near  Grand  Marais.  They  are  opaque, 
and  exhibit  concentric  structure  in  layers  of  various  shades  of  color> 
such  as  olive-green,  flesh-red,  cream,  and  white.  There  are  often 
several  centers  of  structure  in  a  single  pebble,  giving  a  unique  and 
pleasing  effect.  The  pebbles  range  up  to  an  inch  in  diameter,  and 
in  cutting  are  simply  rounded  so  as  to  best  bring  out  the  various 
colors  and  centers  of  structure.  The  hardness  of  the  mineral  is  5; 
specific  gravity  2.2-2.4.  Its  luster  is  vitreous  to  pearly.  Its  compo- 
sition is  that  of  a  hydrous  silicate  of  aluminum,  sodium  and  calcium, 
and  its  occurrence  is  almost  wholly  as  a  secondary  mineral  filling  the 
cavities  of  igneous  rocks. 

The  mineral  at  Grand  Marais  has  long  been  known  as  thomsonite, 
and  is  generally  sold  under  that  name;  but  Professor  N.  H.Winchell 
affirms  that  it  is  in  reality  the  allied  mineral  mesolite.  ( i/ 


192 


PREHNITE 

This  mineral  affords  a  semi-transparent  stone,  which,  when  of  a  deep 
oil-green  color,  may  have  a  limited  use  in  jewelry.  It  does  not  often  occur 
in  nature  in  the  form  of  large  distinct  crystals,  but  usually  as  aggre- 
gates of  minute  crystals,  in  firm  incrusting  masses,  with  a  radiated 
structure.  Portions  of  these  masses,  when  of  a  uniform  color,  form, 
when  cut  en  cabochon,  pleasing  stones. 

In  composition  prehnite  is  a  hydrous  silicate  of  aluminum  and  cal- 
cium, having  the  percentages :  silica  43.7,  alumina  24.8.  It  is  easily 
fusible  before  the  blowpipe  and  is  attacked  by  acids.  Its  hardness 
is  6.65;  specific  gravity  2.80-2.95;  its  luster  is  vitreous.  Its  occur- 
rence is  almost  wholly  in  connection  with  basic  eruptive  rocks,  in  the 
veins  and  cavities  of  which  it  forms  a  secondary  mineral. 

Some  of  the  most  richly  colored  prehnite  known  is  obtained  at  Pater- 
son  and  Bergen  Hill,  New  Jersey.  In  the  Lake  Superior  region  prehnite 
accompanies  native  copper,  and  affords  a  stone  which  is  considered 
worthy  of  cutting.  Many  localities  in  the  Alps  furnish  prehnite,  and 
handsome  pieces  are  obtained  by  polishing  masses  occurring  in'^China. 
Some  prehnite  comes  from  the  Cape  of  Good  Hope,  and  when  cut 
is  known  as  "Cape  chrysolite." 


193 


RHODONITE 

Rhodonite  is  a  silicate  of  manganese,  of  a  pink,  or  flesh-red  color. 
It  does  not  furnish  transparent  gems,  but  occurring  massive  in  large 
pieces  affords  material  for  table-tops,  vases,  jewel-boxes,  paper-weights, 
and  other  large  objects  in  which  such  a  color  is  desired.  The  stone 
has  a  slight  translucency,  which  heightens  its  effect  when  polished, 
and  it  is  also  like  jade  in  being  quite  tough.  The  Russians  use  it  more 
extensively  perhaps  than  any  other  people,  often  introducing  it  into 
ornamental  and  decorative  works,  and  it  is  a  stone  especially  prized 
by  the  Imperial  family.  The  hardness  of  rhodonite  is  5.5-6.5 ;  its  spe- 
cific gravity  3.4-3.7.  Before  the  blowpipe  it  fuses  easily  and  becomes 
black.  It  crystallizes  in  the  triclinic  system.  Its  chemical  composition 
when  pure  is,  silica  45.9,  manganese  protoxide  54.1.  Rhodonite  occurs 
in  a  number  of  localities,  the  district  of  Ekaterinburg,  in  the  Urals, 
affording  that  used  by  the  Russians.  Here  it  occurs  in  a  massive, 
marble-like  form.  At^Cummington,  Massachusetts,  according  to  Kunz, 
large  quantities  of  a  pink  and  red  color  occur  which  have  been  used 
for  ornamental  objects.  A  feature  of  this  rhodonite  is  its  being  mottled 
and  streaked  with  black,  which  causes  it  to  blend  prettily  with  silver. 
Rhodonite  of  the  variety  of  fowlerite,  that  is,  containing  zinc,  occurs 
among  other  zinc  ores  at  Franklin,  New  Jersey.  It  is  sometimes  used 
for  ornamental  purposes. 


194 


598 


Satin  Spar,  polished  (Italy). 

Thulite,  polished  (Norway). 

Serpentine,  polished  (Cornwall,  England). 


ORNAMENTAL,  STONES.  «««« 

Smithsoiiite,  polished  (Greece). 
Serpentine,  polished  Cornwall,  England). 
Serpentine,  polished  (Cornwall,  England;. 


ZOISITE 

Another  rose-red  massive  stone  is  furnished  by  the  variety  of  zoisite 
known  as  thulite.  This  resembles  rhodonite  in  color  somewhat,  but 
is  easily  distinguished  by  its  chemical  characters,  zoisite  being  a  hydrous 
silicate  of  calcium  and  aluminum.  It  is  somewhat  harder  than  rhodo- 
nite, its  hardness  being  6-6.5.  The  name  thulite  is  from  Thule, 
an  ancient  town  of  Norway,  and  the  occurrence  of  thulite  is  confined 
almost  exclusively  to  that  country.  Its  use  for  ornamental  purposes 
is  very  limited;  but  it  answers  well  where  objects  of  its  particular 
color  are  desired. 


PRECIOUS   SERPENTINE 

This  mineral  resembles  jade  in  appearance  and  properties,  and  is 
suited  to  many  of  the  ornamental  uses  to  which  the  former  is  put. 
Not  a  little  so-called  jade  is  doubtless  serpentine.  The  hardness  of 
serpentine  is  somewhat  below  that  of  jade,  it  being  5.5,  and  lower.  It 
is  also  lighter,  its  specific  gravity  being  2.50-2.65.  The  blowpipe  and 
chemical  characters  also  distinguish  it,  serpentine  being  practically 
infusible  before  the  blowpipe,  and  decomposed  by  acids,  while  jade  is 
more  or  less  fusible,  and  not  attacked  by  acids.  In  composition  serpen- 
tine is  a  hydrous  magnesium  silicate  having  the  percentages,  silica  44.1, 
magnesia  43.0,  and  water  12.9.  Like  jade  it  does  not  crystallize,  but 
occurs  in  massive  forms,  which  show  crystalline  structure.  One  of  the 
most  pleasing  properties  of  serpentine  is  its  luster,  which  is  subresinous 
to  oily.  This,  coupled  with  translucency  which  characterizes  most  pre- 
cious serpentine,  and  the  excellent  polish  which  it  takes,  make  the  stone 
of  rich  effect. 

The  color  of  precious  serpentine  is  primarily  some  shade  of  green,  vary- 
ing from  yellowish-green  to  blackish-green.  This  color  may  be  uniform 
or  mottled,  or  may  include  spots  of  other  minerals,  such  as  the  white  of 
calcite,  as  in  several  of  the  serpentine  marbles,  or  cherry-red  from  iron 
oxide,  as  in  the  serpentine  of  Lizard,  England.  The  name  serpentine 
alludes  to  the  green,  serpent-like  cloudings  best  seen  in  serpentine  marble. 

195 


Precious  serpentine  is  obtained  in  many  parts  of  the  world,  among 
the  localities  being  Afghanistan  (which  furnishes  an  almost  transparent 
variety  in  large  masses),  the  Island  of  Corsica,  Fahlun  and  Gulso  in 
Sweden,  the  Isle  of  Man,  and  the  Lizard,  Cornwall,  England. 

In  the  United  States  a  rich  green  variety  of  serpentine,  known  as 
williamsite,  is  found  in  Texas,  Lancaster  County,  Pennsylvania,  and  is 
cut  into  various  charms  and  ornaments.  It  varies  in  color  from  dark 
green  to  light  apple-green.  A  golden  to  greenish  -  yellow  serpentine 
occurs  at  Montville,  New  Jersey,  which  would  admit  of  use  for  the 
manufacture  of  small  objects,  such  as  dishes  and  charms. 

A  variety  of  serpentine  known  as  bowenite  is  found  near  Smithfield, 
Rhode  Island,  varying  in  color  from  pure  white  to  deep  green. 

£<A  dark  green  serpentine  occurs  at  Santa  Catalina  Island,  California, 
which  is  of  sufficient  homogeneity  to  be  turned  into  dishes  of  various 
shapes,  some  being  seven  or  eight  inches  in  diameter. 

Serpentine  marble,  which  usually  consists  of  a  mixture  of  serpentine 
and  calcite,  forms  quite  extensive  deposits  at  several  localities  in  the 
country,  among  which  may  be  mentioned  Moriah,  New  York ;  Dublin, 
Harford  County,  Maryland ;  National  City,  California ;  and  Valley, 
Washington.  This  is  used  like  marble  as  slabs  for  table-tops  and  wall 
decorations. 

Coarse,  common  serpentine  forms  extensive  rock  masses,  and  moun- 
tains of  it  exist ;  but  the  use  of  the  mineral  for  ornamental  purposes  is 
confined  to  pieces  of  pleasing  color,  homogeneity,  and  translucency. 


196 


MALACHITE 

Malachite  is  a  green  carbonate  of  copper  containing  water,  the  per- 
centages being  in  the  typical  mineral:  cupric  oxide  71.9,  carbon  dioxide 
19.9,  and  water  8.2.  It  is  the  common  form  which  copper  assumes 
when  it,  or  even  its  ores,  oxidize  in  the  air.  Many  of  the  green  stains 
on  rocks,  or  minerals,  can  be  correctly  referred  to  malachite.  It  is  only 
valued  for  ornamental  purposes,  however,  when  it  occurs  in  compact 
masses,  usually  exhibiting  concentric  layers.  Malachite  in  this  form 
takes  a  fine  polish.  Malachite  is  not  a  hard  mineral,  its  hardness  being 
between  3.5  and  4.  It  can,  therefore,  be  scratched  with  a  knife.  It 
is  comparatively  heavy,  weighing  four  times  as  much  as  an  equal 
bulk  of  water.  When  heated  before  the  blowpipe  it  fuses  easily, 
coloring  the  flame  green.  By  heating  long  enough  on  charcoal  it  can 
be  made  to  yield  a  globule  of  copper.  It  is  easily  attacked  by  com- 
mon acids,  causing  effervescence  of  carbon  dioxide.  This  test  can 
be  used  to  distinguish  it  from  the  silicate  of  copper,  chryscolla,  which 
has  the  same  color. 

Besides  its  occurrence  in  massive  forms,  as  noted  above,  malachite 
not  uncommonly  is  found  in  tufts  and  rosettes  incrusting  other  min- 
erals. This  is  an  especially  common  occurrence  in  mines  in  Arizona, 
and  affords  specimens  of  great  beauty,  especially  when  the  green  tufts 
of  malachite  are  seen  upon  brown  limonite,  for  then  the  appearance 
of  moss  on  wood  is  closely  simulated.  Such  material  is,  of  course, 
too  fragile  to  be  used  for  decorative  purposes. 

Malachite  is  prepared  for  ornamental  use  by  sawing  masses  of  the 
character  of  those  previously  referred  to  into  thin  strips,  which  are 
then  fastened  as  a  veneer  on  vessels  of  copper,  slate,  or  other  stone 
previously  turned  to  the  desired  shape.  Putting  pieces  together  so  that 
neither  by  their  outlines  nor  color  will  it  appear  that  they  are  patch- 
work, requires  a  high  degree  of  skill,  and  such  work  is  done  almost 
exclusively  in  Russia.  Table  tops,  vases,  and  various  other  vessels  are 
manufactured  in  this  way,  and  form  objects  of  great  beauty.  The  pillars 
of  the  Church  of  Isaac,  in  St.  Petersburg,  are  of  malachite  prepared  in 
this  way,  and  there  are  similar  pillars  in  the  Church  of  St.  Sophia,  Con- 
stantinople, said  to  have  been  taken  from  the  Temple  of  Diana  at  Ephesus. 

197 


Occasionally  the  desired  object  can  be  turned  from  a  single  piece 
of  malachite;  but  pieces  of  sufficient  size  for  this  purpose  are  rare. 
Bauer  describes  one  piece  found  in  the  Gumeschewsk  mines  which  was 
17^  feet  long,  8  feet  broad,  and  3^  feet  high,  and  compact  throughout. 
This  is  probably  the  largest  single  mass  known. 

Russia  furnishes  most  of  the  malachite  suitable  for  work  of  this 
kind,  and  the  art  of  cutting  and  fitting  the  stone  is  possessed  almost 
exclusively  in  that  country.  Most  of  the  Russian  malachite  has  been 
obtained  from  the  mines  of  Nizhni-Tagilsk  and  Bogoslowsk,  in  the 
northern  Urals,  or  Gumeschewsk,  in  the  southern.  The  supply  has 
gradually  decreased  till  now  only  the  Nizhni-Tagilsk  mines  are  pro- 
ductive. The  malachite  occurs  there  in  veins  in  limestone. 

Besides  the  Urals,  fine  malachite,  suitable  for  cutting,  comes  from 
Australia.  Burra  Burra,  in  New  South  Wales,  and  Peak  Downs,  in 
Queensland,  are  localities  whence  good  Australian  malachite  is  obtained. 

Malachite,  as  a  mineral,  is  common  in  copper  mines  in  the  United 
States;  but  it  is  only  in  Arizona  that  it  is  found  of  a  quality  suitable 
for  cutting.  A  variety  from  Morenci,  Arizona,  consists  of  malachite 
and  azurite,  and  gives  a  combination  of  green  and  blue  that  is  unique 
and  pleasing.  Less  use  has  been  made  of  such  material  for  ornamental 
purposes  than  might  have  been,  for  most  of  it  has  unfortunately  been 
smelted  as  a  copper  ore. 

Malachite  is  rarely  used  for  rings,  or  small  jewels,  being  cut  most 
extensively  into  earrings,  bracelets,  inkstands,  and  similar  objects.  Art 
objects  of  malachite  seem  to  have  been  in  much  favor  with  Russian  em- 
perors as  gifts  to  contemporaneous  sovereigns,  and  so  bestowed  are  to  be 
seen  in  numerous  palaces  in  Europe.  Perhaps  the  most  famous  of  these 
gifts  is  the  set  of  center-tables,  mantelpieces,  ewers,  basins,  and  vases 
presented  by  the  Emperor  Alexander  to  Napoleon,  and  still  to  be  seen 
in  an  apartment  of  the  Grand  Trianon  at  Versailles. 

Malachite  was  well  known  to  the  ancients,  and  like  other  precious 
stones  was  worn  as  an  amulet.  It  was  called  pseudo  -  emerald  by 
Theophrastus.  Its  name  is  from  the  Greek  malake,  the  word  for 
mallows,  and  was  given  doubtless  on  account  of  its  green  color. 

It  was  regarded  in  the  sixteenth  century  as  a  powerful  anaesthetic, 
being  used  internally  or,  applied  to  the  injured  parts.  It  was  also  used 
as  a  purgative  and  to  increase  the  strength  and  growth  of  children.  The 
Chinese  still  ascribe  magical  properties  to  vases  made  from  it. 

Azurite,  the  blue  mineral  which  often  accompanies  malachite,  is  like-  „ 
wise  a  hydrous  carbonate  of  copper,  and  occasionally  occurs  so  that  it 
can  be  used  with  malachite  for  ornamental  purposes. 

198 


CHRYSOCOLLA 

This  mineral  in  its  pure  state  is  too  soft  to  be  used  as  a  gem, 
but  mixed  with  quartz,  or  constituting  practically  a  stain,  it  affords 
blue  and  green  stones,  resembling  turquois  on  the  one  hand  and  chryso- 
prase  on  the  other.  In  fact,  it  is  not  unlikely  that  some  of  the  so-called 
turquois  obtained  in  Utah  and  Nevada  is  in  reality  chrysocolla.  Typically 
chrysocolla  is  a  hydrous  silicate  of  copper,  having  the  percentages :  silica, 
34.3,  copper  oxide,  45.2,  and  water,  20.5.  It  thus  resembles  dioptase 
in  composition,  but  unlike  that  mineral  it  does  not  crystallize.  Its 
hardness  varies  from  2  to  that  of  quartz  if  mixed  with  that  mineral. 
Its  specific  gravity  is  slightly  greater  than  that  of  quartz.  Its  blowpipe 
reactions  do  not  differ  from  those  of  turquois  essentially,  because  of  the 
content  of  copper  in  the  latter,  but  chrysocolla  gives  no  test  for  phos- 
phoric acid. 

When  of  good  color  and  hardness  chrysocolla  affords  a  stone  resem- 
bling turquois  or  chrysoprase. 

Chrysocolla  occurring  in  Nizhni-Tagilsk,  in  the  Urals,  is  of  a  sky- 
blue  color,  and  is  known  as  demidovite.  It  has  been  cut  to  some  extent. 
In  our  own  country  chrysocolla  occurs  in  numerous  copper  mines,  espe- 
cially in  Michigan,  Arizona,  and  Nevada,  but  not  much  use  has  yet  been 
made  of  it  in  jewelry. 

The  name  chrysocolla  is  from  the  Greek,  and  means  gold  glue.  It 
was  so  called  from  its  resemblance  to  a  substance  used  by  the  ancients 
for  soldering  gold.  It  is  mentioned  by  Pliny,  and  was  probably  known 
to  the  Romans,  though  not  used  for  ornamental  purposes. 


199 


DIOPTASB 

The  name  of  "  copper  emerald,"  by  which  this  mineral  is  sometimes 
known,  well  indicates  both  its  composition  and  appearance.  No  other 
mineral  so  closely  imitates  the  emerald  in  color,  although  it  differs  in 
being  slightly  darker  and  less  transparent.  It  possesses  also  a  distinct 
rhombohedral  cleavage,  so  prominent  as  to  give  the  mineral  its  name, 
from  two  Greek  words  dia,  through,  and  optomai,  to  see,  because  the 
cleavage  can  be  seen  on  looking  into  a  crystal.  Dioptase  is  a  hydrous 
silicate  of  copper,  having  the  percentage  composition:  silica  38.2,  cupric 
oxide  50.4,  water  11.4.  It  crystallizes  in  the  rhombohedral  division 
of  the  hexagonal  system,  forming  short  prismatic  crystals  resembling 
superficially  an  isometric  dodecahedron.  Its  chemical  characters  suffi- 
ciently distinguish  it  from  emerald,  as  it  gives  before  the  blowpipe  the 
green  flame  of  copper,  and  gelatinizes  with  hydrochloric  acid.  Its  chief 
defect  as  a  gem  consists  in  its  lack  of  hardness,  which  is  only  5.  It  is 
therefore  rather  easily  scratched.  Its  specific  gravity  is  somewhat  high, 
3.28-3.35.  It  has  vitreous  luster,  and  is  brittle. 

The  best  dioptase  comes  from  the  Kirghese  Steppes  of  Siberia,  where 
it  occurs  on  the  hill  Altyn  Tube,  occupying  seams  in  a  compact  lime- 
stone. The  crystals  here  are  so  perfect  that  they  can  be  worn  uncut. 
Small  crystals  and  rolled  pieces  are  found  in  auriferous  sands  in  various 
places  in  the  Jeniseian  Government  in  Russia,  and  fine  crystals  are 
reported  from  the  Mindouli  mine  in  the  French  Congo  State.  It  has 
also  been  obtained  at  the  copper  mines  of  Clifton,  Arizona,  but  the 
crystals  are  small,  and  of  little  value  for  gem  purposes. 


200 


LAPIS  LAZULI 

This  stone  was  the  sapphire  of  the  Greeks,  Romans,  and  Hebrew 
Scriptures.  Pliny  likened  it  to  the  blue  sky  adorned  with  stars.  Large 
quantities  of  worked  pieces  of  it  are  found  in  early  Egyptian  tombs, 
and  the  Chinese  have  long  held  it  in  high  esteem.  Marco  Polo  visited 
Asiatic  mines  of  the  mineral  in  1271  A.  D.,  and  these  had  doubtless 
been  worked  for  a  long  time  previous.  Besides  its  value  as  a  stone,  it 
was  in  former  times  used  as  a  blue  pigment,  giving  the  ultramarine-blue. 
In  modern  times  not  only  has  the  esteem  in  which  the  stone  is  held  for 
ornamental  purposes  declined,  but  the  mineral  can  be  artificially  made 
so  as  to  give  the  desired  blue  color  for  paints,  and  thus  the  use  of  the 
natural  lapis  lazuli  has  greatly  diminished.  It  is  still,  however,  carved 
to  make  vases,  small  dishes,  brooches,  and  ring  stones,  and  is  used  to  a 
considerable  extent  for  mosaic  work.  When,  also,  pieces  of  sufficient 
size  and  of  a  uniform  color  can  be  found,  large  carved  objects  may  be 
made  which  command  a  high  price. 

The  stone  known  as  lapis  lazuli  as  it  occurs  in  nature  is  not  a  single 
mineral  but  a  mixture  of  several,  among  which  are  calcite,  pyrite,  and 
pyroxene.  From  these,  however,  it  is  possible  to  separate  a  mineral  of 
uniform  composition  sometimes  crystallized  in  dodecahedrons,  which  is 
probably  the  essential  ingredient  of  the  stone.  This  mineral  is  known 
as  lazulite,  and  in  composition  is  a  silicate  of  soda  and  alumina,  with  a 
small  quantity  of  sodium  sulphide.  It  is  by  making  a  substance  of  this 
composition  that  the  artificial  ultramarine  is  produced.  The  artificial  is 
said  to  be  as  good  as  the  natural  for  a  pigment,  and  can  be  produced  for 
a  three-hundredth  part  of  the  cost.  The  natural  lapis  lazuli  has  a  hard- 
ness of  5^  and  a  specific  gravity  about  like  that  of  quartz.  It  is  quite 
opaque.  In  color  it  is  blue,  varying  from  the  prized  ultramarine  to  paler, 
and  at  times  is  of  a  greenish  shade.  It  is  said  the  pale  colored  portions 
can  be  turned  darker  by  heating  to  a  red  heat.  When  the  variety  from 
Chile  is  heated  in  the  dark  it  emits  a  phosphorescent  green  light.  The 
stone  in  nature  is  often  flecked  with  white  calcite.  Portions  so  affected 
are  not  considered  as  valuable  as  the  uniform  blue.  Grains  of  pyrite 
are  also  usually  scattered  through  the  stone,  giving  the  "  starry  "  effect 
referred  to  by  Pliny. 

201 


Lapis  lazuli  usually  occurs  in  'limestone,  but  in  connection  with  gran- 
ite, so  that  it  seems  to  be  a  product  of  the  eruption  of  the  granite  through 
the  limestone.  The  lapis  lazuli  of  best  quality  comes  from  Asia,  the 
mines  being  at  Badakschan,  in  the  northeastern  part  of  Afghanistan,  on 
the  Oxus  River.  The  mining  is  done  by  building  great  fires  on  the  rocks 
and  throwing  water  on  them  to  break  them.  The  yield  at  present  is 
small,  not  over  1,500  pounds  a  year  being  obtained.  The  lapis  lazuli 
from  these  mines  is  distributed  all  over  Asia,  going  chiefly  to  China  and 
Russia.  The  price  realized  is  said  to  be  from  $50  to  $75  per  pound. 
Lapis  lazuli  of  poorer  quality  comes  from  a  region  at  the  western  end  of 
Lake  Baikal  in  Siberia.  The  only  other  important  locality  is  in  the  Andes 
Mountains  of  Chile  near  the  boundary  of  the  Argentine  Republic.  This 
material  is  not  much  used  at  the  present  time,  on  account  of  its  poor 
quality,  but  it  was  employed  by  the  Incas  for  decorative  purposes.  One 
mass  24x12x8  inches,  doubtless  from  this  locality,  was  found  in  a  Peru- 
vian grave,  and  is  one  of  the  largest  masses  of  lapis  lazuli  known. 

The  walls  of  a  palace  at  Zarskoe-Selo,  Russia,  built  by  order  of 
Catherine  II.,  are  entirely  lined  with  slabs  of  lapis  lazuli  and  amber. 
Pulverized,  the  stone  was  used  as  a  tonic  and  purgative  by  the  Greeks 
and  Romans,  and  as  late  as  the  sixteenth  century  was  supposed  to  be  a 
cure  for  melancholy.  The  name  lapis  lazuli  means  blue  stone.  Arme- 
nian stone  is  another  term  by  which  the  stone  is  known  in  trade. 


202 


SMITH80NITE 

This  mineral,  named  after  James  Smithson,  who  founded  the  Smith- 
sonian Institution  in  Washington,  is  a  carbonate  of  zinc  used  chiefly  as 
an  ore  of  that  metal.  It  is  usually  of  a  dull,  earthy  character  and 
poorly  fitted  for  ornamental  purposes.  In  some  occurrences,  however,  it 
exhibits  pleasing  colors  and  a  translucency  reminding  one  of  onyx. 
When  so  occurring  it  may  be  cut  into  ring  stones,  or  even  vases  and 
other  dishes  of  considerable  size  and  beauty.  The  smithsonite  from 
Laurium,  Greece,  is  that  perhaps  most  extensively  used  in  this  way,  its 
color  usually  being  some  shade  of  blue.  From  Siberia  a  beautiful  bright 
green  smithsonite  is  obtained,  the  green  color  being  due  probably  to  a 
little  admixed  copper,  and  from  the  zinc  mines  of  Arkansas  and  Missouri 
a  bright  yellow  form  is  derived,  known  locally  as  "turkey  fat  ore." 
The  yellow  color  here  is  due  to  a  little  cadmium.  All  of  these  forms  of 
smithsonite  exhibit  when  polished  a  rich  luster  and  subtransparency  which 
are  pleasing.  The  hardness  of  the  mineral  is  somewhat  deficient  for 
enduring  wear,  this  being  but  5.  It  is  rather  heavy,  its  specific  gravity 
being  4.3  to  4.4.  It  is  infusible,  but  soluble  in  hydrochloric  acid  with 
effervescence.  When  heated  before  the  blowpipe  a  coating  is  formed, 
which  is  yellow  when  hot  and  white  on  cooling.  These  tests  serve  to 
distinguish  the  mineral  from  any  others  with  which  it  might  be 
confounded. 


203 


ALABASTER 

(CALCITE,  GYPSUM) 

The  term  alabaster  is  derived  from  a  kind  of  ointment  vases  called 
alabastra,  which  the  Egyptians  and  peoples  of  a  later  period  were  accus- 
tomed to  carve  out  of  stone.  This  stone  was  largely  a  stalagmitic  calcite 
obtained  at  Thebes,  but  it  is  probable  that  gypsum  was  also  used  to  some 
extent.  At  the  present  time  the  term  is  used  loosely  for  either  of  these 
minerals  when  employed  for  the  manufacture  of  ornamental  objects, 
although  stalagmitic  calcite  is  now  more  generally  designated  as  onyx. 

Both  calcite  and  gypsum  are  soft  minerals,  the  hardness  of  the 
former  being  3,  and  that  of  the  latter  2.  They  are  not  therefore  fitted 
to  endure  wear,  and  can  only  be  employed  for  objects  such  as  vases, 
boxes,  statuary,  etc.,  not  likely  to  be  subjected  to  much  attrition.  Both 
stalagmitic  calcite,  however,  and  gypsum  take  an  excellent  polish,  and 
preserve  it  if  properly  cared  for. 

The  term  alabaster  when  referred  to  gypsum  is  limited  to  the  fine- 
grained granular  variety  usually  white  or  delicately  shaded.  It  is 
obtained  largely  at  Castelino,  near  Leghorn,  in  Italy,  and  is  used  for 
carvings  of  various  sorts.  Objects  are  often  sold  under  the  names  of 
alabaster  that  have  been  made  out  of  plaster  of  paris  by  molding.  These 
can  be  distinguished  from  true  alabaster  by  their  lack  of  translucency. 

Another  form  of  gypsum  used  for  ornamental  purposes  is  that  known 
as  satin  spar.  This  is  white,  with  a  delicately  fibrous  structure,  and 
exhibits  when  polished  a  beautiful  silky  luster  and  pearly  opalescence. 
Large  quantities  of  this  cut  in  the  form  of  necklaces,  charms,  etc.,  are 
often  sold  at  Niagara  Falls  and  vicinity  to  tourists  as  made  from  material 
found  at  the  Falls.  Although  gypsum  occurs  there,  it  is  not  in  this  form, 
and  the  material  used  in  this  way  is  really  obtained  in  Wales. 

Objects  made  from  calcite  can  usually  be  detected  by  their  softness, 
as  they  scratch  easily  and  deeply  with  a  knife,  and  by  their  effervescing 
when  touched  with  a  drop  of  any  common  acid.  In  the  form  of  Mexican 
onyx  calcite  is  extensively  used  for  ornamental  purposes,  and  many 
locally  fashioned  stones,  such  as  the  Petoskey,  Michigan,  fossil  corals 
(often  called  agates),  and  the  Gibraltar  stone,  of  Gibraltar,  belong  to  this 
mineral  species. 

204 


°r  +  +F 


.- 


*<*?  J/?> 


AMB.EK,  MALACHITE,  LA-flS-LAZULI  AND  AZURITE. 


Lapis-lazuli,  polished  (Siberia). 


517 


Malachite  and  Azurite,  polished  (Arizona;. 
IMahichite,  polished  (Australia). 


Amber,  polished,  showing  insects  enclosed  (Coast  of  Baltic  Sea). 


Amber,  rolled  pebble  (Coast  of  Baltic  Sea). 

Malachite,  polished  (Ural  Mountains). 
Malachite  (Arizona). 


AMBER 

Few  minerals  have  been  longer  in  favor  for  ornamental  purposes 
than  amber.  Among  remains  of  the  earliest  peoples,  such  as  the 
Egyptians  and  cave-dwellers  of  Switzerland,  it  is  found  in  carved 
masses,  indicating  that  it  was  highly  prized.  The  Phoenicians  are 
said  to  have  sailed  to  the  Baltic  for  the  purpose  of  procuring  it, 
while  the  Greeks'  knowledge  of  it  is  indelibly  preserved  in  our  word 
electricity,  derived  from  their  word  electron. 

Amber  is  a  fossil  gum  of  trees  of  the  genus  Pinus,  and  is  thus 
a  vegetable  rather  than  mineral  product.  In  color  it  is  yellow,  varying 
to  reddish,  brownish,  and  whitish.  Its  hardness  is  2  to  2.5,  it  being 
slightly  harder  than  gypsum  and  softer  than  calcite.  It  cannot  be 
scratched  by  the  finger  nail,  but  easily  and  deeply  with  a  knife.  It 
is  also  brittle.  Its  specific  gravity  is  scarcely  greater  than  that  of  water, 
the  exact  specific  weight  being  1.05-1.096.  It  thus  almost  floats  in 
water,  especially  sea  water.  It  is  transparent  to  translucent.  On  being 
heated  it  becomes  soft  at  150°  C.,  and  at  250°  to  300°  melts.  It 
also  burns  readily  and  at  a  low  temperature,  a  fact  which  has 
given  rise  to  the  name  of  bernstein,  by  which  the  Germans  know 
it,  and  to'  one  of  the  Roman  names  for  it,  lapis  ardens.  Rubbed  with 
a  cloth  it  becomes  strongly  electric,  attracting  bits  of  paper,  etc.  As 
already  noted,  our  word  electricity  comes  from  the  Greek  for  amber, 
this  seeming  to  be  one  of  the  first  minerals  in  which  this  property 
was  noted.  Amber,  being  a  poor  conductor  of  heat,  feels  warm  rather 
than  cold  in  the  hand,  contrary  to  most  minerals.  It  is  attacked  but 
slowly  by  alcohol,  ether,  and  similar  solvents,  a  property  by  which 
it  may  be  distinguished  from  most  modern  gums  and  some  other  fossil 
ones.  In  composition  it  is  an  oxygenated  hydrocarbon,  the  percentages 
of  these  elements  being  in  an  average  sample:  carbon,  78.94,  hydro- 
gen, 10.53,  and  oxygen,  10.53.  The  mineralogical  name  of  amber 
is  succinite,  a  word  derived  from  the  Latin  succum,  juice.  One  of  its 
constituents  is  the  organic  acid  called  succinic  acid. 

The  present  source  of  most  of  the  amber  of  commerce  is  the  Prussian 
coast  of  the  Baltic  Sea,  between  Memel  and  Dantzig,  although  it  is 
found  as  far  west  as  Schleswig-Holstein  and  the  Frisian  Islands,  and 

205 


even  occasionally  on  the  shores  of  Denmark,  Norway,  and  Sweden. 
From  time  immemorial  pieces  of  amber  have  been  cast  upon  the  shore 
in  these  localities,  and  their  collection  and  sale  has  afforded  a  livelihood 
to  coast-dwellers.  Such  amber  is  called  sea  stone,  or  sea  amber,  and 
is  superior  to  that  obtained  by  mining,  since  it  is  usually  of  uniform 
quality,  and  not  discolored  and  altered  on  the  surface.  Owing  to  its 
lightness,  the  amber  is  often  found  entangled  in  seaweed,  and  the 
collectors  are  accustomed  to  draw  in  masses  of  seaweed  and  search 
them  for  amber.  Amber  so  obtained  is  called  scoopstone,  nets  being 
sometimes  used  to  gather  in  the  seaweed.  In  the  marshy  regions  men 
on  horseback,  called  amber  riders,  follow  the  outgoing  tide  and  search 
for  the  yellow  gum.  It  is  also  searched  for  by  divers  to  some  extent. 
From  the  earliest  times  the  title  to  this  amber  has  vested  in  the  State, 
and  its  collecting  has  been  done  either  under  State  control,  or  as  at 
present,  when  a  tax  is  levied  by  the  government  upon  it.  This  tax 
is  levied  on  the  amber  that  is  mined,  as  well  as  that  obtained  from 
the  sea,  and  brings  a  revenue  at  the  present  time  of  about  $200,000. 

Up  to  1860  the  methods  of  procuring  amber  were  largely  confined 
to  obtaining  it  in  the  manner  above  noted.  As  it  was  evident,  however, 
that  the  sea  amber  came  from  strata  underneath,  and  that  if  either 
by  dredging  or  mining  these  strata  could  be  reached  a  much  larger 
supply  .could  be  obtained,  exploration  was  carried  on  by  mining  methods 
with  successful  results,  and  the  principal  amount  of  the  amber  of  com- 
merce is  now  so  obtained.  The  strata,  as  shown  in  the  mines  of  Sammland, 
the  rectangular  peninsula  of  East  Prussia,  where  most  of  the  mining 
is  carried  on,  are :  First,  a  bed  of  sand ;  below  this  a  layer  of  lignite 
with  sand  and  clay;  and  following  this  a  stratum  of  green  sand, 
fifty  or  sixty  feet  in  thickness.  While  all  these  strata  contain  scattered 
pieces  of  amber,  it  is  at  the  bottom  of  the  green  sand  layer  that  the 
amber  chiefly  occurs,  in  a  stratum  four  or  five  feet  thick,  and  of  very 
dark  color.  It  is  called  the  "  blue  earth."  This  stratum  is  of  Tertiary 
age,  and  there  can  be  no  doubt  that  its  amber  represents  gum  fallen 
from  pines,  which  grew  at  this  period,  and  whose  woody  remains  are 
represented  to  some  extent  in  the  layer  of  lignite.  It  is  probably  true, 
as  Zaddach  remarks,  that  the  amber  has  been  collected  here  from  older 
deposits.  One  of  the  most  interesting  proofs  of  the  vegetable  origin 
of  amber  is  the  occurrence  in  it  of  insects,  sometimes  with  a  leg  or  wing 
separated  a  little  distance  from  the  body,  showing  that  it  had  struggled 
to  escape.  These  insects  include  spiders,  flies,  ants,  and  beetles,  and 
even  the  feather  of  a  bird  has  been  found  thus  preserved.  Indeed, 
the  amber  deposits  have  furnished  important  contributions  to  our  knowl- 

206 


edge  of  Tertiary  life.  Inasmuch  as  the  pieces  bearing  such  remains  are 
valued  more  highly  than  ordinary  amber,  unscrupulous  persons  have 
at  times  found  profitable  employment  in  boring  cavities  into  pieces 
of  amber,  introducing  flies  or  lizards  into  them,  and  then  filling  up 
the  hole  with  some  modern  gum  of  the  same  color.  It  is  said  that 
all  amphibious  or  water  animals  seen  in  amber  have  been  introduced 
in  this  way. 

Besides  the  counterfeiting  of  the  inclusions  of  amber  there  are  several 
substitutes  for  the  gum  itself.  These  are  chiefly  celluloid  and  glass, 
the  substitution  of  the  former  being  dangerous  if  used  for  the  embel- 
lishment of  pipes,  on  account  of  its  inflammatory  character.  Celluloid 
can  be  distinguished  from  amber  by  the  fact  that  when  rubbed  it 
does  not  become  electric,  and  gives  off  an  odor  of  camphor  instead 
of  the  somewhat  aromatic  one  of  amber.  It  is  also  quickly  attacked 
by  alcohol,  or  ether,  and  when  scraped  with  a  knife  gives  a  shaving 
rather  than  a  powder,  as  amber  does.  Glass  can  be  distinguished  by 
its  cold  feeling  and  greater  hardness  and  specific  gravity. 

Besides  these  substitutes,  it  has  been  found  possible  by  heating  and 
pressing  the  scraps  of  amber  not  large  enough  for  carving,  to  make 
them  into  a  homogeneous  mass,  which  is  sometimes  sold  as  amber 
and  sometimes  as  amberoid.  Amber  is  worked  to  desired  shapes  by 
turning  it  on  lathes,  or  by  cutting  by  hand.  By  heating  it  in  linseed 
oil  it  becomes  soft,  so  that  it  can  be  bent,  and  often  all  opaque  spots 
can  be  made  to  disappear  by  such  treatment.  The  amber  which  is 
most  highly  prized  of  any  in  the  world  comes  from  Sicily.  Eight  hun- 
dred dollars  have  been  paid  for  pieces  of  this  no  larger  than  walnuts, 
making  their  value  approach  that  of  diamonds.  The  beauty  of  the 
Sicilian  amber  consists  in  the  variety  of  colors  which  it  displays, 
blood -red  and  chrysolite -green  being  not  uncommon;  and  in  the  fact 
that  these  often  exhibit  a  fluorescence,  glowing  within  with  a  light 
of  different  color  from  the  exterior.  Chemically  the  Sicilian  amber 
is  not  the  same  as  the  Prussian,  as  it  contains  less  succinic  acid, 
and  is  somewhat  more  soluble.  In  other  respects  it  is  not  essen- 
tially different.  It  occurs  chiefly  on  the  eastern  and  southeastern  coasts 
of  the  island,  being  washed  up  in  a  manner  very  similar  to  the  Prus- 
sian amber. 

Amber  has  been  found  in  several  places  in  the  United  States,  but 
there  is  little  of  commercial  value.  It  is  mostly  connected  with  the 
Cretaceous  glauconitic,  or  green  sand  deposits  of  New  Jersey,  fragments 
being  frequently  found  there.  This  amber  is  of  yellow  color,  but  not 
so  compact  or  lustrous  as  foreign  amber.  Amber  has  also  been  reported 

207 


from  the  marls  of  North  Carolina,  some  of  the  coal-beds  of  Wyoming, 
and  in  connection  with  lignite  in  Alaska.  In  the  latter  region  the 
natives  are  said  to  carve  it  into  rude  beads. 

Amber  occurs  in  small  quantities  in  several  countries  of  Europe, 
such  as  near  Basel,  in  Switzerland;  near  Paris,  in  France;  and  near 
London,  in  England.  It  is  also  found  in  many  parts  of  Asia,  these 
localities  being  a  source  of  supply  to  the  Asiatic  countries,  such  as 
China  and  India.  Occasionally  amber  is  obtained  from  Mexico  which 
has  the  beautiful  fluorescence  of  the  Sicilian  article,  though  the  exact 
locality  whence  it  comes  is  not  known.  Specimens  of  carved  amber 
are  found  among  the  relics  of  the  Aztecs,  and  it  is  probable  that  they 
used  it  for  incense.  The  early  use  of  amber  by  European  peoples  has 
already  been  referred  to.  There  are  references  to  it  in  the  most  ancient 
literature,  and  worked  masses  of  it  are  found  among  human  relics 
of  the  greatest  antiquity.  Up  to  comparatively  modern  times  it  was 
an  important  article  of  commerce  among  widely  scattered  peoples,  and 
had  much  to  do  with  bringing  about  communication  between  them. 
Together  with  tin  it  was  one  of  the  chief  objects  which  led  the  Romans 
to  penetrate  the  Gallic  regions  to  the  west  and  north  of  the  Mediter- 
ranean, and  Pliny  says  that  "  it  had  been  so  highly  valued  as  an 
object  of  luxury  that  a  very  diminutive  human  effigy  made  of  amber 
had  been  known  to  sell  at  a  higher  price  than  living  men,  even  in 
stout  and  vigorous  health."  One  of  the  most  elaborate  of  the  Greek 
myths  is  that  which  accounts  for  the  origin  of  amber.  It  runs  in 
this  wise:  Phaethon,  undertaking  to  drive  the  chariot  of  his  sun-god 
father,  Helios,  lost  control  of  his  steeds,  and  approaching  too  near 
the  earth  set  it  on  fire.  Jupiter  to  stop  him  launched  a  thunder-bolt 
at  Phaethon,  and  he  fell  dead  into  the  Eridanus.  His  sisters  lamenting 
his  death  were  changed  into  poplars,  and  their  tears  became  amber. 
According  to  another  legend  amber  is  the  tears  of  the  birds  Meleagridae 
who  weep  for  their  brother  Meleager.  Moore  refers  to  this  legend  in 

his  lines: 

"Around  thee  shall  glisten  the  loveliest  amber 
That  ever  the  sorrowing  sea-bird  hath  wept." 

In  the  Odyssey  one  of  Penelope's  admirers  gives  her  an  amber 
necklace,  and  Martial  compares  the  fragrance  of  amber  to  the  fragrance 
of  a  kiss.  Milton  writes  of  amber,  and  Shakespeare  mentions  it  both 
in  "Love's  Labor  Lost"  and  "The  Taming  of  the  Shrew." 

Necklaces  of  amber  are  popular  wedding  presents  among  the  peasants 
of  Prussia. 

The  properties  assigned  to  amber,  both  as  a  charm  and  as  a  medicine, 

208 


have  been  many.  From  the  earliest  times  it  has  been  used  as  an  amulet, 
being  supposed  to  bring  good  luck  and  to  protect  the  wearer  against 
the  evil  eye  of  an  enemy.  Necklaces  of  amber  beads  are  used  to  this 
day  as  preventive,  or  curative,  of  sore  throat,  and  the  Shah  of  Persia 
wears  around  his  neck  a  cube  of  amber  reported  to  have  fallen  from 
heaven  in  the  time  of  Mohammed,  which  is  supposed  to  have  the 
power  of  rendering  its  wearer  invulnerable.  Amber  was  also  taken 
internally  in  former  times  as  a  cure  for  asthma,  dropsy,  toothache, 
and  other  diseases,  and  to  this  day  is  prescribed  by  physicians  in 
France,  Germany,  and  Italy  for  different  ailments. 

The  use  of  amber  for  artistic  and  decorative  purposes  has  declined 
considerably  since  the  Middle  Ages ;  but  magnificent  illustrations  of  its 
employment  for  these  purposes  are  to  be  seen  in  many  European 
museums,  notably  the  Green  Vaults  of  Dresden. 

In  this  country  a  beautiful  collection  of  objects  made  of  amber  is  to 
be  seen  in  the  Boston  Museum  of  Fine  Arts. 

Though  so  soft  and  easily  destructible  a  substance  amber  endures  with 
ordinary  care  as  well  as  the  hardest  stone,  and  many  works  of  art 
formed  from  it  are  well  preserved. 


209 


JET 

Jet  is  a  variety  of  coal  which,  being  compact,  takes  a  good  polish,  and 
hence  can  be  used  in  jewelry.  Its  hardness  is  between  3  and  4,  and 
specific  gravity  1.35.  It  is  a  kind  of  brown  coal  or  lignite,  and  retain- 
ing as  it  does  some  of  the  original  structure  of  the  wood,  is  not  brittle 
and  smutty  as  is  most  coal.  To  be  of  the  quality  desirable  for  cutting 
it  must  be  black,  of  a  uniform  color,  and  have  a  somewhat  fatty  luster. 

The  jet  of  commerce  has  for  a  long  time  come  chiefly  from  Whitby, 
Yorkshire,  England.  It  occurs  here  as  layers  in  schists  of  Upper  Lias 
age.  The  industry  of  mining  and  cutting  the  jet  has  at  times  reached 
extensive  proportions.  In  1855  twelve  hundred  to  fifteen  hundred  arti- 
sans were  employed  in  the  work,  and  the  annual  value  of  the  output  was 
$100,000.  While  Whitby  is  still  the  center  of  the  industry,  the  demand 
for  jet  has  considerably  decreased,  and  the  trade  has  suffered  a  serious 
setback.  The  jet  manufactured  in  England  is  not  all  of  local  origin, 
much  of  it  being  obtained  from  France,  Spain,  Italy,  Wurtemberg,  and 
the  Orient.  Near  the  close  of  the  eighteenth  century  considerable  cut- 
ting of  both  foreign  and  domestic  jet  was  carried  on  in  France,  but  the 
industry  is  now  largely  abandoned.  Good  jet  occurs  in  numerous  locali- 
ties in  America,  especially  in  Colorado,  and  in  Pictou,  Nova  Scotia,  but  it 
cannot  be  cut  profitably  to  compete  with  the  English  product.  In  the 
anthracite  coal  regions  of  Pennsylvania  this  variety  of  coal  is  cut  into  a 
great  variety  of  objects,  which  find  a  more  or  less  extensive  sale.  Jet  is 
employed  chiefly  for  mourning  jewelry.  The  decline  in  its  use  has  come 
partly  from  a  loss  of  its  popularity  and  partly  from  the  substitution  for  it 
of  black  onyx  or  black  glass.  These  latter  can  be  prepared  somewhat 
more  cheaply  than  jet,  and  while  sometimes  fraudulently  substituted  for 
that  mineral,  are  often  preferred  when  an  opportunity  for  a  choice  is 
given.  If  it  is  desired  to  distinguish  jet  from  either  of  these,  it  can  be 
known  by  being  softer  and  lighter,  and  by  having  a  warmer  feeling  in 
the  hand.  Hard  rubber  and  celluloid  are  also  sometimes  substituted  for 
jet,  in  which  case  they  can  be  distinguished  by  the  fact  that  jet  does  not 
give  a  shaving  under  the  knife,  but  crumbles  away.  The  manufactured 
articles  are  usually  also  given  their  form  by  being  pressed  in  molds,  and 
by  close  inspection  traces  of  the  molds  can  be  seen. 

210 


Jet  seems  to  have  been  known  to  the  Romans,  their  word  for  it 
being  "  gagat,"  of  which  jet  is  probably  a  corruption.  The  Greeks  also 
prized  the  mineral,  and  considered  it  when  powdered  and  mixed  with 
wine  a  preventive  of  toothache.  When  mixed  with  beeswax  they 
believed  it  to  be  a  remedy  for  tumors,  and  burned  as  an  incense  it  was 
supposed  to  drive  away  devils. 

Relics  of  the  early  Saxons  also  disclose  numbers  of  jet  ornaments, 
which  show  that  it  was  in  use  among  them. 

Jet  is  sometimes  known  as  "  black  amber,"  a  name  not  inappropriate 
when  the  similarity  in  origin  of  the  two  minerals  is  considered. 


211 


PEARL 

Pearl  is  not  a  mineral  in  the  strict  sense  of  the  word,  but  has  long 
been  associated  with  gems  in  thought  and  use. 

Like  amber,  jet,  and  coral,  pearls  are  a  product  of  organic  or  living 
forces,  not  of  inorganic  nature.  Mollusks,  chiefly  of  the  order  of  bivalves, 
are  the  organisms  which  produce  pearls.  They  are  a  product,  however, 
not  of  health  and  normal  life,  but  of  disease  and  abnormal  conditions. 
This  is  well  known  by  the  pearl-fishers,  so  that,  in  searching  for  pearls, 
they  pass  by  the  young,  well -formed  mollusks,  to  gather  only  those 
appearing  old,  diseased,  and  distorted.  The  formation  of  pearls  by  a 
mollusk  is  generally  believed  to  be  the  result  of  some  persistent  irrita- 
tion of  the  mantle.  The  agent  of  irritation  has  been  thought  to  be  a 
grain  of  sand,  a  bit  of  seaweed,  an  infusorian,  a  parasite,  or  an  egg  of  the 
mollusk  itself.  The  origin  of  the  pearl  has  been  supposed  to  be  due  to 
an  effort  on  the  part  of  the  mollusk  to  protect  itself  from  such  an  irri- 
tant as  one  of  those  above  mentioned  by  secreting  over  it  a  calcareous 
deposit  similar  to  that  of  which  it  forms  its  shell. 

Some  recent  investigations  by  Dr.  H.  L.  Jameson  of  London  go  to 
show  that  many  free  pearls  originate  through  the  entry  of  a  trematode 
worm  into  the  epithelium  of  the  mantle  of  a  pearl-bearing  mussel.  The 
mussel,  in  order  to  protect  itself  against  the  parasite,  deposits  pearly 
matter  around  it.  Even  if  the  parasite  leaves  the  mantle  the  formation 
of  the  pearl  will  continue.  The  life  history  of  this  parasite  is  interesting 
in  that  at  different  times  it  lives  in  three  hosts.  The  first,  in  the  region 
where  Dr.  Jameson  studied  it,  is  a  so-called  "tapestry  shell,"  the  second 
the  pearl  mussel,  and  the  third  two  members  of  the  duck  family.  The 
eggs  of  the  parasite  passing  out  with  the  faeces  of  the  duck  enter  the 
body  of  the  tapestry  shell,  then  pass  to  the  mussel,  and  when  the  latter 
is  eaten  by  the  duck,  reach  the  intestine  of  the  latter.  This  knowledge 
makes  it  seem  likely  that  it  will  be  possible  ere  long  to  infect  pearl- 
bearing  mollusks  with  the  parasite  in  large  quantities,  and  hence  to 
greatly  increase  the  production  of  pearls. 

The  deposit  of  pearl  has  the  color  and  character  of  the  interior  of 
the  shell,  or  if  the  color  of  the  shell  varies  in  different  portions,  that  of 
the  part  of  the  shell  which  is  nearest.  Unless  the  interior  of  the  shell 

212 


possesses  the  peculiar  nacreous  luster  desired  in  pearls,  these  will  be 
of  no  value. 

The  form  and  size  of  the  pearls  produced  by  mollusks  varies  con- 
siderably. Only  those  which  are  perfectly  spherical  or  drop-shaped  are 
considered  of  first  quality  for  jewelry,  but  these  are  only  a  small  part  of 
the  forms  produced.  Irregular  protuberances  or  convexities  often  distort 
the  spherical  form,  and  highly  complex  and  grotesque  shapes  occur.  One 
such  pearl  is  known  having  a  remarkable  resemblance  to  a  bust  of 
Michael  Angelo.  Others  resemble  insects  or  fruits.  These  resemblances 
can  be  enhanced  by  proper  mounting  and  the  addition  of  a  little  gold 
and  enamel.  Some  fanciful  work  of  this  kind  has  been  done,  and  a  large 
collection  of  such  pearls  is  preserved  in  the  Green  Vaults  in  Dresden. 
Such  pearls  are  known  as  baroques,  and  formerly  had  comparatively 
little  value,  but  at 
the  present  time  they 
are  being  employed 
in  the  most  costly 
jewelry.  Not  infre- 
quently the  pearl  be- 
comes attached  to 
the  interior  of  the 
shell,  as  is  the  one 
shown  in  the 
colored  plate.  Such 
pearls  can  be  used  by 
cutting  them  away 
from  the  shell,  but 
they  have  much  less  value  than  those  well  formed  on  all  sides.  Loose 
pearls  which  form  flat  on  one  side  are  called  button  pearls,  and  are  worth 
only  about  twenty-five  per  cent  less  than  round  pearls.  Again,  pearls  may 
be  hollow.  Such  are  called  coque  de  perle,  and  have  little  value  if  their  hol- 
low nature  be  known.  This,  however,  is  not  always  the  case,  as  is  shown  by 
an  instance  mentioned  by  Kunz,  of  a  New  York  lady  who  had  purchased 
a  pearl  apparently  of  good  quality,  except  for  a  little  black  spot  on  one 
side.  This  was  mounted  and  worn  as  an  article  of  jewelry  until,  while 
its  owner  was  applauding  at  the  opera  one  evening,  the  pearl  broke  and 
disclosed  its  interior  filled  with  a  white,  greasy  clay. 

The  Chinese  take  advantage  of  the  habit  of  mollusks  to  cover  any 
intruded  substance  with  pearl,  to  introduce  into  the  shells  of  these 
animals,  under  the  mantle,  beads  and  small  images.  The  mollusk  is 
returned  to  the  water,  and  in  about  a  year's  time  taken  out  again,  when 

213 


Shell  showing  images  of  Buddha  inserted  during  the  life  of 
a  mollusk  and  then  covered  with  a  pearly  deposit.   After  Kunz 


the  objects  are  found  to  be  coated  with  a  pearly  substance.  Pearls  so 
formed,  however,  are  comparatively  dark  and  lusterless,  and  have  by 
no  means  the  value  of  those  of  wholly  natural  origin. 

Pearls  vary  in  size  from  those  of  microscopic  dimensions  to  those  as 
large  as  a  pigeon's  egg.  The  latter  are,  of  course,  very  rare. 

The  Shah  of  Persia  is  said  to  possess  the  largest  pearl  known,  it 
being  about  one  and  one-third  inches  in  length  in  one  direction  and  one 
inch  in  another.  A  pearl  in  the  Austrian  crown  weighs  300  carats,  and 
one  in  the  South  Kensington  Museum  weighs  455  carats.  The  small 
pearls  used  in  jewelry  are  known  as  seed,  dust,  or  sand  pearls. 

Pearls  are  chiefly  white  in  color,  but  many  are  tinted  yellow  or  pink; 
some  are  gray,  green,  or  purple,  and  many  other  colors  occur.  Black 
pearls  are  obtained  in  certain  fisheries.  The  pearls  from  the  Unios  of 
North  America  are  of  almost  every  shade. 

Pearls  of  pure  white  color,  if  of  the  proper  luster,  are  those  most 
highly  prized  in  Europe  and  America,  although  a  slight  pinkish  tinge 
does  not  injure  the  value.  They  must,  however,  have  the  transparency 
of  the  true  pearl  and  not  be  "  chalky."  In  China  and  India  pearls  of 
yellow  color  are  preferred. 

The  hardness  of  pearl  is  4,  and  its  specific  gravity  2.65-2.68.  It  is 
thus  like  that  of  shell  or  "  mother  of  pearl,"  which  might  be  expected 
from  the  fact  that  both  are  of  the  same  chemical  composition — carbonate 
of  lime.  Owing  to  their  low  hardness  pearls  are  easily  scratched,  and  on 
account  of  their  composition  are  attacked  by  acids.  They  thus  deterio- 
rate with  age,  losing  their  polish  and  luster  and  often  becoming  black  and 
unsightly.  No  way  of  positively  restoring  the  luster  of  pearls  is  known, 
although  occasionally  the  outer  marred  coating  can  be  removed  by  those 
skilled  in  the  art,  and  a  lustrous  surface  be  found  beneath. 

The  Ceylonese  are  accustomed  to  feed  pearls  which  have  become  dull 
to  chickens.  After  the  pearl  has  remained  in  the  crop  of  the  bird  a  few 
hours  the  fowl  is  killed  and  the  pearl  removed.  The  movement  and 
friction  to  which  the  pearl  has  been  subjected  in  the  bird's  crop  are 
usually  found  to  have  restored  its  luster  to  some  extent. 

To  preserve  pearls  as  long  as  possible  they  should  be  wiped  with  a 
clean  linen  cloth  each  time  after  being  worn,  and  be  kept  in  a  dust-tight 
box  carefully  wrapped  in  linen.  Hot  or  boiling  water  injures  and  in 
time  destroys  their  luster,  and  many  valuable  pearls  have  been  ruined 
because  the  mollusk  which  contained  them  was  boiled  before  opening. 

The  mollusks  which  yield  pearls  are  many,  and  pearl-fishing  is  an 
industry  carried  on  in  many  parts  of  the  globe. 

The  pearl  mollusk  or  pearl  oyster,  par  excellence,  is  that  known  by 

214 


the  scientific  name  of  Meleagrina  (Avicula)  margaritifera.  This  mollusk 
has  a  bivalve  shell  averaging  seven  or  eight  inches  in  diameter,  and  gen- 
erally thick.  The  exterior  is  of  a  greenish-black  color,  while  the  interior 
is  silver -white  with  pearly  luster.  The  latter  forms  indeed  the  well- 
known  "mother  of  pearl."  This  mollusk  inhabits  warm  seas,  occurring 
especially  in  sheltered  localities  in  the  Indian  Ocean,  and  occasionally 
throughout  the  tropical  zone  of  the  Pacific  Ocean.  It  groups  itself  in 
colonies  like  the  common  oyster,  usually  on  coral  banks  at  a  depth  of 
twenty  to  thirty  feet.  It  is  not  free  moving,  but  attached  by  a  byssus, 
which  must  be  severed  before  the  mollusk  can  be  brought  to  the  surface. 
The  pearl  fisheries  of  the  Indian  Ocean  chiefly  center  in  the  Straits  of 
Manaar  between  India  and  Ceylon.  The  fishing  is  largely  confined  to  the 
months  of  March  and  April,  as  the  sea  favors  best  at  that  time,  and  at 
that  season  from  fifteen  thousand  to  twenty  thousand  fishers  and  dealers 
are  said  to  gather  along  the  pearl  coasts.  The  oysters  are  obtained  by 
divers,  who  go  out  in  boats  and  secure  the  shells  by  diving.  They 
usually  dive  without  appliances,  and  work  under  the  water  simply  by 
holding  their  breath  for  the  time.  Some  fishers,  however,  make  use  of 
diving  suits  and  bells.  The  work  is  dangerous,  not  only  on  account  of 
the  bodily  strain,  but  because  sharks  prey  upon  the  divers.  The  oysters 
are  unloaded  from  the  boats  into  pits  on  the  shore,  where  they  are  left 
to  putrefy,  and  the  pearls  are  then  washed  out. 

Other  localities  in  the  Orient  where  the  pearl  oyster  occurs,  and 
where  pearl-fishing  is  carried  on  in  the  same  manner  as  above  described, 
are  the  Persian  Gulf,  the  Red  Sea,  and  the  Sulu  Archipelago.  The  Red 
Sea  fisheries  furnished  in  earlier  times  an  extensive  supply  of  pearls,  and 
were  probably  the  source  of  those  used  by  the  Romans.  They  are  now, 
however,  largely  exhausted.  The  Persian  Gulf  pearls  are  inferior  in  color 
to  those  of  Ceylon,  and  are  known  as  "Bombay"  pearls.  The  Ceylon 
fisheries  are  under  control  of  the  colonial  government,  and  are  carefully 
guarded  to  prevent  exhaustion  of  the  supply.  The  localities  where  the 
fishers  are  to  work  are  staked  off,  and  when  an  area  has  once  been 
worked  over  it  is  allowed  to  lie  "'fallow"  for  seven  years,  so  as  to  allow 
a  new  crop  to  grow. 

So  far  as  the  American  continent  is  concerned,  the  true  pearl  oyster 
is  found  chiefly  in  the  Gulf  of  California.  It  occurs  here  both  on  the 
east  and  west  coast,  and  as  far  south  on  the  Pacific  coast  as  the  northern 
boundary  of  Guatemala.  It  is  also  found  on  the  Brazilian  coast  and 
the  western  shores  of  South  America. 

The  California  pearl  fisheries  were  in  operation  at  the  time  of  the 
invasion  by  Cortez,  and  he  sent  a  number  of  fine  pearls  which  he 

215 

\ 


obtained  there  to  the  queen  of  Spain.  Since  that  time  the  fisheries 
have  been  carried  on  with  a  varying  degree  of  persistence  from  time 
to  time,  the  beds  having  occasionally  become  practically  sxhausted 
through  too  reckless  dredging.  The  right  to  work  the  beds  is  held 
by  the  Mexican  government,  and  the  fisheries  are  leased  by  it  to  differ- 
ent companies.  Both  the  shells  and  the  pearls  are  of  value,  the  sales 
of  the  one  reaching  as  high  a  figure  as  of  the  other.  Black  pearls 
are  the  specialty  of  these  fisheries,  and  some  of  the  finest  known 
have  been  found  here.  The  total  annual  product  from  the  fisheries 
reaches  at  the  present  time  a  value  of  half  a  million  dollars  a  year. 
American  pearls  are  known  in  trade  as  "Panama"  pearls,  and  bring 
a  somewhat  lower  price  than  those  of  the  Orient. 

Besides  the  pearl  oyster  of  the  sea,  a  number  of  mussels  which 
make  their  home  in  the  beds  of  fresh-water  streams  or  lakes  produce 
fine  pearls.  These  mollusks  belong  chiefly  to  the  family  Uwonida, 
and  include  many  species.  They  are  bivalves,  and  live  both  in  the 
beds  of  running  streams  and  in  still  bodies  of  water  on  muddy  bottoms. 
They  are  usually  to  be  found  at  a  depth  below  the  surface  of  the  water 
of  from  two  to  twenty  feet.  They  lie  either  on  the  surface  of  the 
mud,  or  partly  imbedded  in  it,  and  with  their  valves  slightly  open, 
to  allow  access  of  water  containing  oxygen  and  food.  At  the  slightest 
touch  the  valves  close,  and  remain  so  until  danger  is  past.  The  lumber- 
men of  Canada  take  advantage  of  this  peculiarity  to  collect  the  mollusks 
for  food  by  tying  bushes  on  the  rear  of  their  rafts  as  they  float  down 
stream,  to  which  the  clams  attach  themselves  in  considerable  num- 
bers. A  somewhat  similar  method  is  pursued  by  the  fishermen  of  the 
Mississippi  Valley,  who  collect  the  clams  in  great  numbers  for  the 
manufacture  of  pearl  buttons.  They  row  about  with  long  iron  rods 
fastened  across  their  boats,  from  which  at  intervals  series  of  hooks 
and  chains  dangle  in  the  water,  and  to  these  the  mollusks  attach 
themselves.  The  mollusks  are  removed  from  their  shells  by  boiling, 
hence  any  pearls  which  they  might  contain  are  rendered  worthless. 
The  same  method  of  fishing  might,  however,  be  used  to  gather  shells 
for  pearls.  Other  methods  used  to  gather  the  mollusks  to  search  for 
pearls  are:  raking  the  bottom  with  an  iron  rake;  wading  with  naked 
feet,  and  picking  up  any  projecting  shell  as  it  is  felt;  or  systematic 
dredging.  The  use  of  a  water  telescope  is  said  to  facilitate  the  work 
of  individual  search  for  mollusks  likely  to  contain  pearls.  It  consists 
simply  of  a  long,  light,  wooden  box,  one  end  of  which  is  strapped 
to  the  face,  while  the  other,  covered  with  glass,  is  immersed  in  the 
water.  Provided  with  this  appliance  the  bottom  of  a  river  or  lake  can 

216 


be  searched  carefully.  Enormous  quantities  of  the  Unios  are  destroyed 
in  the  search  for  pearls,  and  the  supply  has  become  considerably 
diminished  in  consequence.  This  waste  might  be  avoided  if  care  was 
used  in  opening  the  shell  not  to  injure  the  animal.  This  work  is  per- 
formed in  Germany  by  a  thin  blade  of  steel  about  an  inch  in  width, 
and  bent  at  a  right  angle  about  an  inch  from  the  end.  The  thin 
blade  is  inserted  between  the  valves,  and  then  turned  at  right  angles 
so  that  the  shell  is  opened  the  width  of  the  blade.  The  operator  can 
then  feel  about  for  pearls,  and  if  none  are  found  return  the  mollusk 
to  the  water  without  having  injured  it.  The  search  for  pearls  in  this 
country  is  usually  carried  on  by  persons  out  of  regular  employment, 
and  has  rarely  been  reduced  to  a  systematic  occupation.  The  total 
value  of  the  pearls  which  have  been  obtained,  however,  is  great,  and 
their  price  is  steadily  increasing.  One  of  the  first  valuable  pearls  found 
in  this  country  was  obtained  near  Paterson,  New  Jersey,  in  1857.  This 
pearl  brought  at  its  first  sale  $2,500,  and  is  to-day  worth  $10,000. 
A  sky-blue  pearl  weighing  ninety-three  grains,  found  at  Caney  Fork, 
Tennessee,  in  1897,  was  sold  in  London  for  $3,300.  Pearls  valued 
at  from  $100  to  $1,000  are  frequently  found  in  the  waters  of  the 
interior  States,  such  as  Wisconsin,  Minnesota,  and  Arkansas.  In  Arkansas 
large  numbers  of  valuable  pearls  have  been  found  loose  in  the  streams, 
so  that  many  of  the  pearl-hunters  are  of  the  opinion  that  the  mollusks 
"  shed  "  their  pearls  at  intervals.  While  the  region  of  the  Mississippi 
Valley  is  that  in  which  the  pearl -bearing  mollusks  chiefly  abound, 
they  occur  also  in  the  waters  of  the  Eastern  States,  and  these  furnish 
an  appreciable  supply. 

The  common  oysters  and  clams  of  the  temperate  sea  coasts  pro- 
duce pearls  no  less  than  those  of  fresh  waters;  but  they  lack  the 
desired  luster  and  transparency,  and  are  considered  of  no  value.  Some 
gastropod,  or  univalve  mollusks,  also  produce  pearls,  among  which 
may  be  mentioned  the  Strombus  of  the  West  Indies  and  the  Turritella 
of  the  East  Indies.  These  pearls  are  of  rose  tint,  but  are  liable  to  fade, 
and  lack  also  the  transparency  of  the  true  pearl. 

Pearls  seem  to  have  been  valued  by  peoples  of  all  times,  both  civilized 
and  uncivilized.  The  Hebrew  Scriptures  make  frequent  references  to 
them,  and  there  are  many  incidents  in  history  showing  the  esteem 
in  which  they  were  held  by  the  Greeks  and  Romans.  The  best  known 
of  these  is  probably  Cleopatra's  wager  with  Antony,  that  at  a  single 
meal  she  would  swallow  the  value  of  a  whole  province.  In  pursuance 
of  this  boast  she  is  said  to  have  dissolved  a  pearl  of  great  value  in 
a  glass  of  sour  wine,  and  then  to  have  drank  the  wine.  It  may  be 

217 


worth  noting  that  this  story  cannot  be  literally  true,  since  a  pearl 
of  the  size  reported  would  only  slightly  dissolve  in  such  a  mixture. 
If  ground  to  a  fine  powder,  however,  the  pearl  might  be  swallowed 
in  the  wine  without  injury  to  the  system,  and  if  this  was  done  the 
story  can  be  credited.  According  to  Pliny  the  wealthy  Romans  were 
accustomed  to  mix  pearls  with  their  wine,  presumably  in  this  way, 
to  improve  the  flavor  of  the  beverage.  The  name  for  the  pearl  among 
the  Romans  and  Greeks  was  Margarita,  and  the  finest  pearls  are  still 
known  by  this  term. 

The  Romans  believed  that  pearls  were  solidified  drops  of  dew, 
which  had  fallen  into  the  gaping  shells  of  oysters.  The  size  and 
quality  of  the  pearl  were  supposed  to  depend  on  the  size  of  the  dewdrop 
and  the  purity  of  the  air.  Ancient  Hindoo  authorities  describe  pearls  as 
originating  in  elephants,  clouds,  boars,  fishes,  frogs,  and  oysters,  the  latter 
being  the  most  productive.  In  their  view  the  effect  of  the  pearl  upon  its 
wearer  varied  with  its  color.  A  light  yellow  pearl  brought  wealth,  one 
more  deeply  colored,  understanding,  a  white  pearl,  fame,  and  a  blue  one, 
good  luck. 

Among  the  Chinese  and  Hindoos  to  this  day  pearls  are  regarded  as 
of  great  medicinal  value,  and  a  large  proportion  of  the  imperfect  pearls 
obtained  in  the  fisheries  are  used  for  this  purpose.  They  are  considered 
beneficial  in  syncope,  hemorrhage,  and  stomach  troubles,  and  seed  pearls 
are  mixed  with  sweetened  water  for  use  as  a  stimulant.  Among  the 
Arabians  and  Persians  pearls  are  used  as  a  cure  for  insanity  and  all 
mental  diseases;  for  diseases  of  the  heart,  stomach,  and  bowels;  and  for 
bleeding  and  skin  diseases.  A  similar  belief  in  the  efficacy  of  pearls  for 
the  cure  of  insanity  existed  in  Europe  as  late  as  the  seventeenth  century. 
The  insane  King  of  Spain,  Charles,  was  given  pearl  powder  mixed 
with  distilled  water  as  a  remedy.  The  Aztecs  and  Incas  of  America, 
when  first  visited  by  the  Spaniards,  possessed  quantities  of  pearls  of  the 
finest  luster  and  color.  Large  numbers  of  pearls  are  found  in  the 
prehistoric  mounds  of  America  also,  showing  that  even  these  people 
held  them  in  esteem.  These  pearls  generally  lack  the  luster  of  the 
pearl  of  the  present  day ;  but  whether  this  has  been  lost  through  lapse 
of  time,  or  whether  the  Mound  Builders  were  content  with  pearls  that 
would  to  modern  people  seem  valueless,  is  not  known.  The  mound 
pearls  are  frequently  found  bored  and  strung. 

The  passion  for  pearls  for  ornament  continues  at  the  present  day, 
and  they  often  command  even  higher  prices  than  the  diamond,  weight 
for  weight.  The  price,  however,  depends  so  much  upon  individual 
quality  that  no  fixed  scale  of  values  can  be  given. 

218 


Emanuel  gives  the  following  qualifications,  as  necessary  to  a  per- 
fect pearl:  "  . 

1.  It  must  be  perfectly  round,  or  drop-shaped,  seeming  as  if  fashioned 
or  turned  into  shape. 

2.  It  must  have  a  perfectly  pure  white  color. 

3.  It  must  be  slightly  transparent. 

4.  It  must  be  free  from  specks,  spots,  or  blemish. 

5.  It  must  possess  the  peculiar  luster  characteristic  of  the  gem. 
Pearls  are  sold  by   their   weight   in 

grains,  rather  than  by  carats,  four  grains 
equaling  a  carat.  Seed  pearls  weighing 
one  grain  are  usually  worth  from  one  to 
three  dollars  each.  With  the  increase 
in  size,  however,  the  increase  in  price  is 
rapid,  a  two-grain  pearl  being  worth,  for 

instance,  four  times  as  much   as  a  one-  

grain   pearl,    a    three-grain    pearl    nine  ^*^  ™" 

times  as  much,  and  so  on.     The  largest 


pearls  bring,  like  the  largest  diamonds, 

individual    prices.      The    pearl    is,  per-  ^^  ^^ 

haps,  the  only  gem  that  does  not  need  ^P  ^BF 

to  have  its  beauties  enhanced  by  cutting,  ^^_  ^^_ 

nor  can  any   polishing   process  improve  ^J 

its  surface.      The  favorite  use  of  pearls  ^^ 

20      ^A  22 

is  to  string  them  in  necklaces ;  but  they  ^^v 

are  also  often  set  around  other   stones  ^^^ 

to  heighten  their  effect,  or  they  are  used  2B  W  • 
alone  in  rings. 

There    are    numerous  ways  of   pro-  Bx»ct  sizes^of^earjsfrom  2  to  30 

ducing   imitation  pearls,  one   of   which, 

invented  many  years  ago  by  a  French  bead-maker  named  Jacquin,  gives 
remarkably  accurate  reproductions.  The  Jacquin  pearls  are  made  from 
an  easily  fusible  bluish  glass,  which  is  first  drawn  into  tubes,  and  from 
these,  hollow  globules  of  the  desired  size  are  blown.  These  are  covered 
on  the  inside  with  a  solution  of  isinglass,  and  a  substance  called  essence 
of  pearl,  which  is  blown  in  warm,  and  spread  over  the  interior  by 
rapid  motion.  When  dry,  the  globules  are  filled  with  wax.  The  essence 
of  pearl,  which  constitutes  the  important  feature  of  Jacquin's  process, 
consists  of  a  silvery  substance  found  beneath  the  scales  of  the  fish 
known  as  the  bleak  (Cyprinus  alburnus).  It  is  in  the  form  of  thin, 
irregular  rhombic  plates,  and  is  obtained  by  washing  the  scales,  one 

219 


pound  of  essence  being  derived  from  seven  pounds  of  scales.  From 
eighteen  thousand  to  twenty  thousand  fish  are  required  to  produce 
the  latter  amount  of  scales.  The  substance  is,  therefore,  costly;  and 
owing  to  this  fact,  and  the  amount  of  labor  and  skill  required  to  make 
the  pearls,  they  bring  a  considerable  price.  They  can  be  distinguished 
from  genuine  pearls  by  their  greater  hardness,  and  a  colder  feeling 
in  the  hand.  The  holes  in  the  false  pearls,  moreover,  are  comparatively 
large,  and  have  a  blunt  edge,  while  those  made  in  real  pearls  are  small, 
and  have  a  sharp  edge.  False  pearls  are  sometimes  made  by  turning 
pieces  of  mother-of-pearl  into  a  spherical  form;  but  they  are  clumsy 
imitations,  and  can  be  at  once  detected  by  the  difference  of  luster 
as  a  whole,  and  the  variations  of  luster  on  different  surfaces.  A  very 
good  imitation  of  black  pearls  is  made  by  cutting  pieces  of  hematite 
into  a  spherical  form.  These  counterfeit  the  luster  of  the  black  pearl 
in  a  remarkable  degree;  but  can  be  distinguished  by  their  greater 
weight  and  hardness. 


220 


Dredging  Precious  Coral 


PRECIOUS   CORAL 

Of  the  great  number  of  forms  and  species  of  coral  known  a  single 
one  furnishes  nearly  all  that  is  used  in  jewelry.  This  species  is  known 
by  the  scientific  name  of  Corallium  rubrum,  and  belongs  to  the  family 
Gorgonidae  of  the  group  Alcyonaria.  It  is  a  branching  coral,  shrub-like 
in  its  appearance,  and  grows  to  a  height  of  a  foot  or  more,  with  stems 
an  inch  in  diameter.  If  the  living  coral  be  examined  it  will  be  found 
to  consist  of  an  outer  fleshy  or  gelatinous  portion  inclosing  an  inner, 
hard,  calcareous  skeleton.  The  outer  portion  is  made  up  of  numbers  of 
polyps,  as  the  little  coral  animals  are  called,  joined  together.  The  pro- 
jecting polyps  look  in  life  like  little  warts  over  the  surface.  Each  has 
eight  tentacles.  The  internal  skeleton  differs  from  that  of  the  majority 
of  corals  in  being  red  in  color.  When  the  coral  animals  die  this  internal 
skeleton  is  left,  and  by  polishing  it  the  coral  of  jewelry  is  obtained.  This 
kind  of  coral  grows  almost  exclusively  in  the  Mediterranean  Sea.  The 
localities  where  it  is  most  abundant  are  the  coasts  of  Algiers  and  Tunis, 
the  western  coasts  of  Sardinia  and  Corsica,  portions  of  the  coast  of 
Sicily,  the  western  coast  of  Italy,  and  a  few  localities  on  the  southern 
coasts  of  France  and  Spain.  The  coral  forms  banks  at  depths  of  from 
ninety  to  one  hundred  feet,  growing  up  from  the  bottom.  That  of  the 
greater  depths  has  not  as  rich  color  as  that  nearer  the  surface,  and  does 
not  grow  to  so  large  a  size.  The  work  of  dredging  the  coral  is  per- 
formed by  fleets  of  small  vessels  manned  by  crews  of  from  six  to  twelve 
persons.  Work  is  carried  on  only  in  the  summer  months  because  of  the 
stormy  weather  at  other  seasons.  The  vessels  are  obliged  to  put  out 
about  six  miles  to  sea  in  order  to  reach  the  best  fishing-grounds,  and  the 
work  is  of  a  laborious  and  dangerous  sort.  The  dredging  is  performed 
by  means  of  an  appliance  consisting  of  two  heavy  oaken  sticks  bound 
together  in  the  shape  of  a  cross,  from  the  ends  of  which  hang  ropes 
upon  which  are  fastened  nets  with  meshes  of  different  sizes.  On  being 
sunk  to  the  bottom  by  means  of  a  heavy  stone,  the  nets  of  the  dredge 
entangle  branches  of  coral,  or  they  are  attached  by  divers,  and  upon 
drawing  to  the  surface  the  coral  can  be  picked  off.  The  price  obtained 
for  the  raw  coral  is  from  four  to  seven  dollars  per  pound,  each  vessel 
securing  from  three  hundred  to  four  hundred  pounds  in  a  season. 

221 


The  industry  is  almost  exclusively  in  the  hands  of  Italians,  although 
originally  carried  on  by  the  French.  The  latter  are  said  to  be  striving, 
by  means  of  subsidies  and  in  other  ways,  to  regain  control  of  the  indus- 
try, especially  on  the  Algerian  coasts.  The  production  from  this  region 
alone  amounts  to  twenty-two  thousand  pounds  yearly.  The  cutting 
and  working  of  the  coral  is  carried  on  chiefly  in  factories  in  the  cities 
of  Genoa,  Leghorn,  and  Marseilles.  The  value  of  the  crude  coral 
varies  considerably  according  to  its  quality.  If  the  coral  polyps  have 
died  before  a  branch  is  brought  to  the  surface,  the  coral  turns  black, 
and  its  value  is  thus  considerably  decreased.  On  /the  shores  of  Sicily 
a  large  proportion  of  dead  coral  is  brought  up,  and  the  proportion 
is  continually  increasing.  The  cause  is  believed  to  be  quantities 
of  volcanic  ash  thrown  from  the  neighboring  volcanoes,  which  make 
the  water  too  muddy  for  the  polyps.  Some  of  the  coral  found  is  con- 
siderably worm-eaten,  and  this  sort  is  highly  valued  in  some  parts 
of  India,  although  regarded  worthless  in  Europe.  The  particular  shade 
of  coral  most  highly  valued  by  Europeans  varies  from  time  to  time. 
At  one  time  the  bright  red  was  preferred,  then  a  pale  pink,  or  rose  color, 
came  into  fashion,  and  now  the  red  seems  to  be  most  in  favor  again. 
The  color,  whatever  it  is,  should  be  uniform  to  make  a  piece  of  coral 
of  the  best  quality.  The  forms  into  which  coral  is  cut  include  beads, 
buttons,  ear-ring  drops,  cameos,  and  carvings  of  various  sorts.  Polished 
pieces  of  branches  an  inch  or  two  in  length  are  often  worn  in  bunches, 
either  as  brooches  or  in  the  form  of  bracelets  and  necklaces.  These 
were  supposed  in  former  times  to  act  as  a  charm  to  ward  off  bad  luck 
and  evil  spirits.  Coral  is  especially  prized  by  dark-skinned  people, 
such  as  the  Italians,  Moors,  Persians,  and  Hindoos,  because  its  color 
harmonizes  well  with  their  complexion.  The  Chinese  also  use  immense 
quantities  of  it,  although  the  effect  in  color,  as  contrasted  with  that 
of  the  wearer,  is  less  favorable  to  them. 

Precious  coral  seems  to  have  been  known  and  prized  by  the  Greeks 
and  Romans.  The  Greeks  called  it  gorgeia,  and  believed  that  it 
originated  from  the  blood  which  dripped  from  the  head  of  Medusa, 
and  which  becoming  hard  was  planted  by  sea-nymphs  in  the  sea. 
In  the  Middle  Ages  precious  coral  was  used  in  medicine  as  an  as- 
tringent, and  was  given  to  newly  born  infants.  It  was  also  given 
together  with  a  preparation  of  pearls  as  a  cure  for  vomiting  and 
colic.  It  was  supposed  to  be  a  heart  stimulant  and  to  cure  fevers 
and  poisonings.  Hung  on  fruit-bearing  trees  it  protected  them  from 
hail  and  blighting  winds  and  gave  fertility.  It  was  worn  by 
children  as  a  preventive  against  children's  diseases,  and  infants  were 

222 


supposed  to  be  protected  in  their  sleep  by  having  a  piece  tied  round 
their  necks. 

To  this  day  the  Brahmins  and  Fakirs  of  the  East  place  coral  upon 
their  dead  to  prevent  evil  spirits  taking  possession  of  the  corpse,  while 
in  Egypt  it  is  taken  internally  as  a  tonic  after  being  treated  with  lemon 
and  burned. 

Coral  is  imitated  in  celluloid,  also  by  a  mixture  of  marble  dust  cemented 
with  glue,  and  stained  with  vermilion.  Beads  of  bone  and  of  gypsum 
are  also  stained  so  as  to  imitate  coral.  These  imitations  can  be  distin- 
guished by  chemical  and  physical  characters,  true  coral  having  a  specific 
gravity  of  2.6-2.7,  and  a  hardness  of  nearly  4.  It  also  effervesces 
with  weak  acid,  which  would  not  be  the  case  with  two  of  the  above 
imitations. 


223 


INDEX 


Abrasives 
Achroite   - 
Adamantine  luster 
Adularia 
Agate 

cutting  of 

Petoskey 
Alabaster 
Albite 

Alexandrite  - 
Allanite 

Almandine  ruby 
Almandite 
Amazonstone 
Amber 

black 

imitations  of 

mining  of 
Amethyst 

Amorphous  substances  defined 
Andalusite 
Andradite 
Anisotropic  media 
Apatite 

Apostolic  gems  - 
Aquamarine 
Armenian  stone 
Asparagus  stone 
Australia,  diamond  fields  of 

opals  of     - 

sapphires  of  - 
Austrian  Yellow  diamond  - 
Aventurine 
Axinite- 
Ax-stone 
Azurite 

Balas  ruby 
Baroque  pearls 
Basanite 
Bernstein 
Beryl 

caesium    - 

golden 
Billitonite 
Birthstones 
Black  amber 


PAGE 

-  47 

111 

16 
179 
154 

48 

204 

204 

178 

106,  107 

-  140 

95 

-  127 
176 

-  205 
211 

-  207 
207 
145 

40 

-  124 
127 

-  26 
185 

65 
98, 102 

-  202 
185 

85 
163 

-  93 
74 

149, 179 
139 

-  167 
198 

95 
213 

-  158 
205 

98 
103 

98,  103 
184 

61 
211 


PAGE 

Black  opal  -  163 

pearl  -  216,  220 

Blue  ground  -  83 

Blood  stone  153,  188 

Blue-John  187 

Bombay  pearl     -  -      215 

Bone  turquois  170 

Borneo,  diamond  fields  of  85 

Bort   -  68 

Bowenite  -  196 

Braganza  diamond  -  -     83,  121 

Brazil,  agate  of  -  -     154 

amethyst  of  145 

andalusite  of  -      124 

chrysoberyl  of     -  106 

diamond  fields  of  75 

euclase  of  104 

rock  crystal  of  -      143 

topaz  of    -  121 

Brazilian  chrysoberyl    -  -     106 

chrysolite  111 

diamond  -     142 

emerald     -  111 

sapphire  -     111 

Brilliant,  double      -  46 

form  of  -       44 

mixed  45 

sizes  of  -       51 

Briolette  46 

British  Guiana  diamond  fields  -       86 

Bronzite         -  169 

Burmah,  jade  of  -     165 

ruby  of     -  89 

Button  pearls     -  -     213 

Cabochon  cut  46 

Cacholong  -     160 

Caesium  beryl  103 

Cairngorm  stone  -      147 

Calcite  204 

California,  diamonds  of  -       87 

tourmaline  of      -  116 

Callainite  -     174 

Cape  chrysolite  193 

Cape  ruby  -      129 

Carat  defined  50 

Carbonado          -           -           -  -       68 


225 


Carbuncle 

Carnelian 

Carnelionyx  - 

Cascalho 

Cat's-eye        -  106,  107, 

Ceylon,  chrysoberyl  of 

essonite  of 

gem  cutting  in    - 

gem  mining  in 

pearl  fisheries  of 

sapphire  of     - 

spinel  of  - 

zircon  of 

Ceylonese  chrysolite 
Ceylonite 
Ceylon  opal  - 
Chalcedony 
Chalcedonyx 
Chalchihuitl 
Chiastolite    - 

Chlorastrolite     ... 
Chloromelanite 
Chrysolite 
Chrysoberyl 
Chrysocolla 
Chrysoprase 
Cinnamon  stone 
Citrine 

Colombia,  emeralds  of 
Colors  of  gems 

as  seen  with  the  dichroscope 
Coral 
Cordierite 
Corundum     - 
Critical  angle 
Crocidolite    - 
Cryptocrystalline  quartz 
Crystal  forms 
Cube 

Cutting  of  gems 
Cyanite    - 
Cymophane  - 

Demantoid 
Demidovite   - 
Derbyshire  spar 
Dewey  diamond 
Diamond 

artificial  production  of  - 

Australian 

Austrian  Yellow  - 

Braganza 

Brazilian  - 

British  Guiana 

cleaning  of  -  - 

colors  of 


PAGE 
130 

-  151 
156 

10,  75 

148,  169 

106 

-  130 

42 
8 

215 
93 
96 

-  109 
132 

96 
178 
150 
156 

-  167 
124 

-  191 
165 

-  132 
106 

-  199 
152 

-  127 
147 

-  100 

13 

33 

221 

-  136 

88 

28 

149 

-  150 

37 

-  39 
41 

-  123 
106,  107 

-  130 
199 
187 

86 
66 
87 
85 
74 

83,  121 
75, 142 

-  86 
82 
68 


PAGE 

Diamond,  combustibility  of  66 

crystal  form  of  .   67 

cutting  of  -      47 

Dresden  Green  -           -       68 

Excelsior  -  83 

Florentine      -  -           -68, 74 

Great  Mogul        -  74 

hardness  of    -  -            -            -        69 

Hope  Blue  -           -             68 

of  India  -            -        71 

Jubilee     -  83 

Kohinoor        -  -           -           -       72 

Lake  George        -  -           142 

luster  of  -       68 

Matura     -  109 

mining  of        -  77 

of  United  States  86 

of  Ural  Mountains  -                       -       85 

origin  in  Brazil    -  80 

origin  in  South  Africa  -       84 

Orloff       -  73 

Pitt  -       72 

Regent     -  72 

Sancy  74 

slaves'      -  120 

sorting  of       -  - 11,  82 

South  African     -  80 

specific  gravity  of  -       69 

Tiffany  83 

Victoria  -       83 

Dichroism     -  31 

Dichroite  -     136 

Dichroscope  33 

Diopside  -     16$ 

Dioptase        -  200 

Dispersion  -       27 

Dispersive  power      -  27 

Disthene  -      123 

Distortion  of  crystals  37 

Distribution  of  gems  -                                 7 

Dodecahedron  40 

Double  brilliant  46 

Double  refraction    -  29 

Doublets  -       56 

Dresden  Green  diamond     -  68 

Effect  of  heat  on  color  of  gems  -       14 

Emerald  98,  99, 158 

confused  with  jade  -                       -     101 

Enstatite  169 

Epidote    -  134 

Eruptive  rocks  6 

Essonite  -     127 

Euclase  104 

Euxenite  -            -      140 

Excelsior  diamond  -                          83 


226 


PAGE 

False  amethyst  - 

186 

Iceland  agate 

chrysolite 

132 

Idocrase 

emerald     ... 

186 

Imitation  coral    - 

lapis     - 

157 

gems 

ruby 

186 

pearls 

topaz    - 

186 

Indicolite 

Feldspar 

175 

India,  bloodstone  of 

Fergusonite  - 

140 

carnelian  of 

Fire  opal 

161 

diamonds  of 

Flame  opal    - 

161 

garnets  of 

Flint 

158 

moss  agate  of 

Florentine  diamond  •         •  -            -     68, 

74 

lolite 

Fluorescence       -            -                       35, 

186 

Isotropic  media 

Fluorite 

186 

Israelitish  gems 

Fluorspar 

186 

Itacolumite 

Fool's  gold     - 

189 

Fowlerite 

194 

Jacinth 

Jade 

Gadolinite     - 

140 

Jadeite 

Gagat       - 
Garnet 
Gems,  apostolic 

211 
127 

65 

Jargon 
Jargoon 
Jasper 

distinguished  from  precious  stones 

3 

Jet      - 

Israelitish 

65 

Job's  tears 

mining  of                                -             8, 

12 

Jubilee  diamond 

mounting  of         - 

48 

nature  of        - 

1 

occurrence  of      - 

4 

Kohinoor  diamond 

Scriptural      .... 

61 

Kunzite 

valuation  of                     - 

50 

Gem  gravels        -                                      5,    9 

Labradorite 

Geyserite 

160 

Lake  George  diamonds 

Gibraltar  stone  - 

204 

Lapis  lazuli 

Girasol 

161 

Lepidolite     - 

Golden  beryl       -                                  98, 

103 

Leucosapphire    - 

Golden  opal  - 

161 

Love's  arrow 

Great  Mogul  diamond  - 

74 

Luster  of  gems, 

Green  star  stone       - 

191 

Lydian  stone 

Grossularite 

127 

Lyncurion 

Gypsum 

204 

Malachite 

Hair  stone 

148 

Marcasite 

Hardness  of  gems     - 

17 

Marekanite 

Harlequin  opal   - 

161 

Matura  diamond 

Hawk's-eye   - 

149 

Menilite 

Heavy  liquids     - 

21 

Mesolite 

Heliotrope 

153 

Metallic  luster    - 

Hematite                                              188, 

220 

Metamorphic  rocks  - 

Hiddenite      -                        - 

118 

Methylen  iodide  - 

Honduras,  opals  of        - 

163 

Mexican  onyx 

Hope  Blue  diamond 

68 

Mining  of  gems  - 

Hornstone                        ... 

158 

Mocha  stone 

Hungarian  opals 

162 

Moldavite 

Hyacinth                                      109,  110, 

116 

Moonstone     - 

Hyalite 

160 

Moss  agate 

Hydrophane        - 

160 

Mountain  mahogany 

Hypersthene 

169 

Mounting  of  gems 

227 

PAGE 
182 

135 
223 
54 
219 
111 
153 
152 
71 
129 
151 
136 
26 
65 
80 

109 

-  165 
165 

-  109 
109 

-  157 
210 

-  133 

83 

-  72 
118 

-  176 
142 

-  201 
117 

88,  94 

148 

16 

158 

-  110 

-  197 
190 

-  181 
109 

-  160 
192 

-  16 

6 

-  22 
156 

-  8,12 

151 

-  183 
178 

-  151 
181 

-  48 


PAGE 

PAGE 

Nature  of  gems 

1 

Phenocrystalline  quartz 

-     141 

Needle  stone 

-      148 

Phosphorescence 

34 

Nephrite        ... 

165 

Pitt  diamond      ... 

-       72 

Nicol  prism         ... 

29 

Plasma 

153 

Nigrine 

137 

Pleochroism 

-       31 

Pleonaste 

96 

Obsidian 

-     180 

Polarization        ... 

29 

Occurrence  of  gems 

4 

Polarizing  apparatus 

30 

Octahedron 

39 

Polycrase 

-      140 

Odontolite     ... 

170 

Pomegranate  ruby    - 

97 

Oeil-de-boeuf 

-     177 

Prase 

152 

Oily  luster     - 

16 

Precious  stones  defined 

3 

Oligoclase            ... 

-     179 

Prehnite 

193 

Olivine           ... 

132 

Pseudo-emerald 

198 

Onyx        .... 

156,  204 

Pyrite 

-     189 

Mexican  ... 

156 

Pyro-electricity 

34 

Opal 

-     159 

Pyrope     - 

127 

black        ... 

163 

fire      -           ... 

-     161 

Quartz 

141 

flame        ... 

161 

aventurine 

-     149 

golden            ... 

-     161 

cryptocrystalline 

150 

harlequin 

161 

phenocrystalline 

-      141 

resin   - 

-     160 

rose 

146 

wax           ... 

160 

rutilated 

148 

Oriental  amethyst 

-       88 

eagenitic 

148 

aquamarine 

88 

smoky 

147 

chrysolite       ... 

88,  106,  132 

emerald 

88,  93 

Radio-active  gems    - 

35 

hyacinth        - 

-       88 

Refraction 

-       26 

topaz         ... 

88 

Regent  diamond 

72 

Orloff  diamond 

-       73 

Resin  opal 

-     160 

Ox-eye           ... 

177 

Resinous  luster 

16 

Rhinestone 

142,  143 

Panama  pearls  ... 

-      216 

Rhodonite     - 

194 

Paste             ... 

55 

Rock  crystal 

-      141 

Pearl        -                       - 

-     212 

Rose  cut 

46 

baroque 

213 

Rose  quartz 

-      146 

black              ... 

216,  220 

Rubicelle 

95 

Bombay    - 

215 

Rubellite 

111,  116 

button 

-     213 

Ruby 

89 

fishing      ... 

-    215,216 

almandine 

95 

fresh  water    - 

-     216 

artificial  production  of  - 

91 

Oriental 

215 

Balas 

-        95 

origin  of         - 

212- 

Cape 

129 

oyster 

215 

pomegranate 

-       97 

Panama 

216 

value  of    - 

89 

preservation  of    - 

214 

Ruby  spinel 

95 

size  of 

-     214 

Rutile 

137 

use  in  medicine  - 

218 

Rutilated  quartz 

-     148 

Pearly  luster 

-       16 

Pendeloque  - 

46 

Sagenite 

148 

Penfield  specific  gravity  balance 

-       21 

Sagenitic  quartz 

148 

Peridot 

132 

Sancy  diamond 

74 

Peristerite 

-     178 

Sapphire  d'eau  - 

136 

Petoskey  agate 

204 

Sapphire 

92 

Piezo-electricity 

-       34 

of  Australia  - 

-       93 

Phenacite      • 

105 

of  Montana 

93 

228 


Sapphire  of  Siam 

star 

water 

Samarskite    - 
Sard 
Sardonyx 
Satin  spar 
Saxon  topaz 
Saxon  chrysolite 
Scale  of  hardness     - 
Scepter  diamond 
Schorl 

Scriptural  gems 
Sedimentary  rocks  - 
Semi-precious  stones  defined    • 
Serpentine     - 
Siberite    - 
Silky  luster  - 
Single  refraction 
Slave's  diamonds 
Smithsonite 
Smoky  quartz 
South  Africa,  diamonds  of 

tiger  eye  of 
Spanish  topaz     - 
Specific  gravity 
Spessartite 
Sphene 
Spinel 

Spinel  ruby  - 
Spodumene 

Star  of  South  Africa  diamond 
Star  of  the  South  diamond 
Star  sapphire 
Step  cut  - 
Strass 

Stream  beds 
Sunstone 

Superstitions  regarding  gems 
Systems  of  crystallization  - 

Table  cut 

Table  of  color 

Table  of  hardness 

Table  of  specific  gravity 

Thomsonite 

Thoulet  solution 

Thulite    - 

Tiffany  diamond 

Tiger-eye 

Titanite 


PAGE 

PAGE 

- 

93 

Topaz 

119 

94 

Brazilian 

120 

- 

136 

Oriental 

88,  121 

140 

Russian    - 

121 

- 

152 

Saxon 

-     121 

156 

Spanish    - 

147 

- 

204 

Touchstone 

-      158 

121 

Tourmaline  - 

111 

- 

132 

colors  of 

-      114 

17 

composition  of 

113 

- 

74 

localities  of    - 

115,  116 

111 

Trap  cut 

45 

- 

61 

Trapezohedron    - 

40 

6 

Turkey-fat  ore 

203 

• 

3 

Turquois 

-     170 

195 

of  Persia 

171 

. 

111 

of  United  States 

-     171 

16 

Tuscan  diamond 

74 

. 

29 

120 

Ultramarine 

201 

_ 

203 

United    States,    occurrence   of 

dia- 

147 

monds  in 

86 

. 

80 

turquois  of     - 

-      171 

149 

Uralian  emerald 

131 

121, 

147 

Ural  Mountains,  aventurine  of  - 

-     150 

19 

chrysoberyl  of 

107 

. 

127 

diamond  fields  of 

85 

138 

euclase  of 

104 

. 

95 

garnet  of 

-     130 

95 

malachite  of 

198 

. 

118 

topaz  of 

-     121 

83 

tourmaline  of 

116 

. 

80 

Uvarovite 

-     127 

94 

a 

45 

Valuation  of  gems 

50 

55 

Variscite  - 

-     174 

. 

4 

Vermeille 

129 

178, 

179 

Vesuvianite 

135 

57 

Victoria  diamond     - 

83 

38 

Viluite     - 

-     135 

Vitreous  luster 

16 

- 

46 
15 

Water  sapphire  - 

-     136 

JUf 

1H 

Wax  opal 

160 

xo 

25 

Waxy  luster 

16 

4M 

Williamsite    - 

196 

- 

192 

22 

Xanthite 

-    135 

- 

195 

X-rays 

35 

68, 

83 

- 

148 

Zircon 

-    109 

138 

Zoisite           ... 

195 

14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


*        3Nov'64FK' 

f 

NOV  9    *64  11  AI 

| 

i»w*     /         un  -  if  ^j 

V 

AUG  1  2  2006 

LD  21A-40m-ll,'63 
(E1602slO)476B 

General  Librarj 
University  of  Calif  c 
Berkeley 

• 


YE  05665 


THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


